// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
    \page qtdesigner-manual.html

    \title Qt Widgets Designer Manual
    \ingroup qttools
    \keyword Qt Widgets Designer

    \QD is the Qt tool for designing and building graphical user
    interfaces (GUIs) with \l {Qt Widgets}. For user interface design with
    \l {Qt Quick}, see \l {Qt Design Studio Manual} {Qt Design Studio}.

    You can compose and customize your windows or dialogs in a
    what-you-see-is-what-you-get (WYSIWYG) manner, and test them using different
    styles and resolutions. Widgets and forms created with \QD integrate
    seamlessly with programmed code, using Qt's signals and slots mechanism, so
    that you can easily assign behavior to graphical elements. All properties
    set in \QD can be changed dynamically within the code. Furthermore, features
    like widget promotion and custom plugins allow you to use your own
    components with \QD.

    \note You have the option of using \l {Qt Quick} and
    \l {Qt Design Studio Manual}{Qt Design Studio} for user interface
    design rather than widgets. It is a much easier way to write many kinds of
    applications. It enables a completely customizable appearance,
    touch-reactive elements, and smooth animated transitions, taking advantage
    of hardware acceleration.

    If you are new to \QD, you can take a look at the
    \l{Getting To Know Qt Widgets Designer} document. For a quick tutorial on how to
    use \QD, refer to \l{A Quick Start to Qt Widgets Designer}.

    \image designer-multiple-screenshot.png {Illustration showing three screenshots
           of the \QD editor on different operating systems}

    \section1 Table of Contents

    \list
        \li  \l{A Quick Start to Qt Widgets Designer}
        \li  \l{Qt Widgets Designer's Editing Modes}
            \list
                \li  \l{Qt Widgets Designer's Widget Editing Mode}{Widget Editing Mode}
                \li  \l{Qt Widgets Designer's Signals and Slots Editing Mode}
                      {Signals and Slots Editing Mode}
                \li  \l{Qt Widgets Designer's Buddy Editing Mode}
                      {Buddy Editing Mode}
                \li  \l{Qt Widgets Designer's Tab Order Editing Mode}
                      {Tab Order Editing Mode}
            \endlist
        \li  \l{Using Layouts in Qt Widgets Designer}
        \li  \l{Saving, Previewing and Printing Forms in Qt Widgets Designer}
        \li  \l{Using Containers in Qt Widgets Designer}
        \li  \l{Creating Main Windows in Qt Widgets Designer}
        \li  \l{Editing Resources with Qt Widgets Designer}
        \li  \l{Using Stylesheets with Qt Widgets Designer}
        \li  \l{Using a Designer UI File in Your C++ Application}
        \li  \l{Using a Designer UI File in Your Qt for Python Application}
    \li Advanced Use
    \list
        \li  \l{Customizing Qt Widgets Designer Forms}
        \li  \l{Using Custom Widgets with Qt Widgets Designer}
        \li  \l{Creating Custom Widgets for Qt Widgets Designer}
        \li  \l{Creating Custom Widget Extensions}
        \li  \l{Qt Widgets Designer's UI File Format}
    \endlist
    \endlist
*/


/*!
    \page designer-to-know.html


    \title Getting to Know Qt Widgets Designer

    \image designer-screenshot.png {Screenshot showing the UI of the \QD
           editor}

    \section1 Launching Designer

    Once you have installed Qt, you can start \QD in the same way as any other
    application on the development host. You can also launch \QD directly from
    Qt Creator. Qt Creator automatically opens all .ui files in the integrated
    \QD, in \gui Design mode.

    Generally, the integrated \QD contains the same functions as the standalone
    \QD. For more information about the differences, see the
    \l{http://doc.qt.io/qtcreator/index.html}{Qt Creator Manual}.

    If you have large forms that do not fit in the Qt Creator \gui Design mode,
    you can open them in the stand-alone \QD.

    \section1 The User Interface

    When used as a standalone application, \QD's user interface can be
    configured to provide either a multi-window user interface (the default
    mode), or it can be used in docked window mode. When used from within an
    integrated development environment (IDE) only the multi-window user
    interface is available. You can switch modes in the \gui Preferences dialog
    from the \gui Edit menu.

    In multi-window mode, you can arrange each of the tool windows to suit your
    working style. The main window consists of a menu bar, a tool bar, and a
    widget box that contains the widgets you can use to create your user
    interface.

    \target MainWindow
    \table
        \row
            \li \inlineimage designer-main-window.png {Screenshot of the
                             \QD showing all components that can be
                             added to the window}
            \li \b{Qt Widgets Designer's Main Window}

        The menu bar provides all the standard actions for managing forms,
        using the clipboard, and accessing application-specific help.
        The current editing mode, the tool windows, and the forms in use can
        also be accessed via the menu bar.

        The tool bar displays common actions that are used when editing a form.
        These are also available via the main menu.

        The widget box provides common widgets and layouts that are used to
        design components. These are grouped into categories that reflect their
        uses or features.
    \endtable

    Most features of \QD are accessible via the menu bar, the tool bar, or the
    widget box. Some features are also available through context menus that can
    be opened over the form windows. On most platforms, the right mouse is used
    to open context menus.

    \target WidgetBox
    \table
        \row
            \li \inlineimage designer-widget-box.png {Screenshot showing all
                             widget components for \QD}
            \li \b{Qt Widgets Designer's Widget Box}

        The widget box provides a selection of standard Qt widgets, layouts,
        and other objects that can be used to create user interfaces on forms.
        Each of the categories in the widget box contain widgets with similar
        uses or related features.

        You can display all of the available objects in a category by clicking
        on the handle next to the category label. When in
        \l{Qt Widgets Designer's Widget Editing Mode}{Widget Editing
        Mode}, you can add objects to a form by dragging the appropriate items
        from the widget box onto the form, and dropping them in the required
        locations.

        \QD provides a scratch pad feature that allows you to collect
        frequently used objects in a separate category. The scratch pad
        category can be filled with any widget currently displayed in a form
        by dragging them from the form and dropping them onto the widget box.
        These widgets can be used in the same way as any other widgets, but
        they can also contain child widgets. Open a context menu over a widget
        to change its name or remove it from the scratch pad.
    \endtable


    \section1 The Concept of Layouts in Qt

    A layout is used to arrange and manage the elements that make up a user
    interface. Qt provides a number of classes to automatically handle layouts
    -- QHBoxLayout, QVBoxLayout, QGridLayout, and QFormLayout. These classes
    solve the challenge of laying out widgets automatically, providing a user
    interface that behaves predictably. Fortunately knowledge of the layout
    classes is not required to arrange widgets with \QD. Instead, select one of
    the \gui{Lay Out Horizontally}, \gui{Lay Out in a Grid}, etc., options from
    the context menu.

    Each Qt widget has a recommended size, known as \l{QWidget::}{sizeHint()}.
    The layout manager will attempt to resize a widget to meet its size hint.
    In some cases, there is no need to have a different size. For example, the
    height of a QLineEdit is always a fixed value, depending on font size and
    style. In other cases, you may require the size to change, e.g., the width
    of a QLineEdit or the width and height of item view widgets. This is where
    the widget size constraints -- \l{QWidget::minimumSize()}{minimumSize} and
    \l{QWidget::maximumSize()}{maximumSize} constraints come into play. These
    are properties you can set in the property editor. For example, to override
    the default \l{QWidget::}{sizeHint()}, simply set
    \l{QWidget::minimumSize()}{minimumSize} and \l{QWidget::maximumSize()}
    {maximumSize} to the same value. Alternatively, to use the current size as
    a size constraint value, choose one of the \gui{Size Constraint} options
    from the widget's context menu. The layout  will then ensure that those
    constraints are met. To control the size of your widgets via code, you can
    reimplement \l{QWidget::}{sizeHint()} in your code.

    The screenshot below shows the breakdown of a basic user interface designed
    using a grid. The coordinates on the screenshot show the position of each
    widget within the grid.

    \image addressbook-tutorial-part3-labeled-layout.png {Screenshot of an
           address book application highlighting all widget components and
           their position}

    \note Inside the grid, the QPushButton objects are actually nested. The
    buttons on the right are first placed in a QVBoxLayout; the buttons at the
    bottom are first placed in a QHBoxLayout. Finally, they are put into
    coordinates (1,2) and (2,1) of the QGridLayout.

    To visualize, imagine the layout as a box that shrinks as much as possible,
    attempting to \e squeeze your widgets in a neat arrangement, and, at the
    same time, maximize the use of available space.

    Qt's layouts help when you:

    \list 1
        \li  Resize the user face to fit different window sizes.
        \li  Resize elements within the user interface to suit different
            localizations.
        \li  Arrange elements to adhere to layout guidelines for different
            platforms.
    \endlist

    So, you no longer have to worry about rearranging widgets for different
    platforms, settings, and languages.

    The example below shows how different localizations can affect the user
    interface. When a localization requires more space for longer text strings
    the Qt layout automatically scales to accommodate this, while ensuring that
    the user interface looks presentable and still matches the platform
    guidelines.

    \table
        \header
            \li  A Dialog in English
            \li  A Dialog in French
        \row
            \li  \image designer-english-dialog.png {Screenshot showing an
                        address book example in English}
            \li  \image designer-french-dialog.png {Screenshot showing an
                        address book example in French}
    \endtable

    The process of laying out widgets consists of creating the layout hierarchy
    while setting as few widget size constraints as possible.

    For a more technical perspective on Qt's layout classes, refer to the
    \l{Layout Management} documentation.
*/


/*!
    \page designer-quick-start.html


    \title A Quick Start to Qt Widgets Designer

    Using \QD involves \b four basic steps:

    \list 1
        \li  Choose your form and objects
        \li  Lay the objects out on the form
        \li  Connect the signals to the slots
        \li  Preview the form
    \endlist

    \image rgbController-screenshot.png {Screenshot showing an RGB controller
           with sliders to change the red, green, and blue value}

    Suppose you would like to design a small widget (see screenshot above) that
    contains the controls needed to manipulate Red, Green and Blue (RGB) values
    -- a type of widget that can be seen everywhere in image manipulation
    programs.

    \table
    \row
    \li \inlineimage designer-choosing-form.png {Screenshot showing a form of a
                     list with all components to add to the window}
    \li \b{Choosing a Form}

    You start by choosing \gui Widget from the \gui{New Form} dialog.
    \endtable


    \table
    \row
    \li  \inlineimage rgbController-arrangement.png {Screenshot showing the
                      arrangement of the rgb controller components}
    \li  \b{Placing Widgets on a Form}

    Drag three labels, three spin boxes and three vertical sliders on to your
    form. To change the label's default text, simply double-click on it. You
    can arrange them according to how you would like them to be laid out.
    \endtable

    To ensure that they are laid out exactly like this in your program, you
    need to place these widgets into a layout. We will do this in groups of
    three. Select the "RED" label. Then, hold down \key Ctrl while you select
    its corresponding spin box and slider. In the \gui{Form} menu, select
    \gui{Lay Out in a Grid}.

    \table
        \row
            \li \inlineimage rgbController-form-gridLayout.png {Screenshot
                             showing the arrangement of the rgb controller
                             components with one component being selected}
            \li \inlineimage rgbController-selectForLayout.png {Screenshot
                             showing the option to Lay Out in a Grid in the
                             \QD editor}
    \endtable


    Repeat the step for the other two labels along with their corresponding
    spin boxes and sliders as well.

    The next step is to combine all three layouts into one \b{main layout}.
    The main layout is the top level widget's (in this case, the QWidget)
    layout. It is important that your top level widget has a layout; otherwise,
    the widgets on your window will not resize when your window is resized. To
    set the layout, \gui{Right click} anywhere on your form, outside of the
    three separate layouts, and select \gui{Lay Out Horizontally}.
    Alternatively, you could also select \gui{Lay Out in a Grid} -- you will
    still see the same arrangement (shown below).

    \image rgbController-final-layout.png {Screenshot showing the result of the
           final layout}

    \note Main layouts cannot be seen on the form. To check if you have a main
    layout installed, try resizing your form; your widgets should resize
    accordingly. Alternatively, you can take a look at \QD's
    \gui{Object Inspector}. If your top level widget does not have a layout,
    you will see the broken layout icon next to it,
    \inlineimage rgbController-no-toplevel-layout.png {Screenshot showing the
                 option for no toplevel layout}
    .

    When you click on the slider and drag it to a certain value, you want the
    spin box to display the slider's position. To accomplish this behavior, you
    need to connect the slider's \l{QAbstractSlider::}{valueChanged()} signal
    to the spin box's \l{QSpinBox::}{setValue()} slot. You also need to make
    the reverse connections, e.g., connect the spin box's \l{QSpinBox::}
    {valueChanged()} signal to the slider's \l{QAbstractSlider::value()}
    {setValue()} slot.

    To do this, you have to switch to \gui{Edit Signals/Slots} mode, either by
    pressing \key{F4} or selecting \gui{Edit Signals/Slots} from the \gui{Edit}
    menu.

    \table
        \row
            \li \inlineimage rgbController-signalsAndSlots.png {Screenshot of the
                             rgb controller showing the signal connection between
                             the slider and spinbox}
            \li \b{Connecting Signals to Slots}

        Click on the slider and drag the cursor towards the spin box. The
        \gui{Configure Connection} dialog, shown below, will pop up. Select the
        correct signal and slot and click \gui OK.
    \endtable

    \image rgbController-configure-connection1.png {Screenshot showing the
           configuration to connect the spinbox with the slider, so the spinbox
           value changes the slider}

    Repeat the step (in reverse order), clicking on the spin box and dragging
    the cursor towards the slider, to connect the spin box's
    \l{QSpinBox::}{valueChanged()} signal to the slider's
    \l{QAbstractSlider::value()}{setValue()} slot.

    You can use the screenshot below as a guide to selecting the correct signal
    and slot.

    \image rgbController-configure-connection2.png {Screenshot showing the
           configuration to connect the slider with the spinbox, so the slider
           changes the spinbox value}

    Now that you have successfully connected the objects for the "RED"
    component of the RGB Controller, do the same for the "GREEN" and "BLUE"
    components as well.

    Since RGB values range between 0 and 255, we need to limit the spin box
    and slider to that particular range.

    \table
        \row
            \li \inlineimage rgbController-property-editing.png {Screenshot
                             showing option to change minimum and maximum
                             value that can be entered in the spinbox}
            \li \b{Setting Widget Properties}

        Click on the first spin box. Within the \gui{Property Editor}, you will
        see \l{QSpinBox}'s properties. Enter "255" for the
        \l{QSpinBox::}{maximum} property. Then, click on the first vertical
        slider, you will see \l{QAbstractSlider}'s properties. Enter "255" for
        the \l{QAbstractSlider::}{maximum} property as well. Repeat this
        process for the remaining  spin boxes and sliders.
    \endtable

    Now, we preview your form to see how it would look in your application -
    press \key{Ctrl + R} or select \gui Preview from the \gui Form menu. Try
    dragging the slider - the spin box will mirror its value too (and vice
    versa). Also, you can resize it to see how the layouts that are used to
    manage the child widgets, respond to different window sizes.
*/


/*!
    \page designer-editing-mode.html
    \previouspage Getting to Know Qt Widgets Designer
    \nextpage Using Layouts in Qt Widgets Designer

    \title Qt Widgets Designer's Editing Modes

    \QD provides four editing modes: \l{Qt Widgets Designer's Widget Editing Mode}
    {Widget Editing Mode}, \l{Qt Widgets Designer's Signals and Slots Editing Mode}
    {Signals and Slots Editing Mode}, \l{Qt Widgets Designer's Buddy Editing Mode}
    {Buddy Editing Mode} and \l{Qt Widgets Designer's Tab Order Editing Mode}
    {Tab Order Editing Mode}. When working with \QD, you will always be in one
    of these four modes. To switch between modes, simply select it from the
    \gui{Edit} menu or the toolbar. The table below describes these modes in
    further detail.

    \table
        \header \li  \li  \b{Editing Modes}
        \row
            \li  \inlineimage designer-widget-tool.png {Designer widget tool icon}
            \li  In \l{Qt Widgets Designer's Widget Editing Mode}{Edit} mode, we can
                change the appearance of the form, add layouts, and edit the
                properties of each widget. To switch to this mode, press
                \key{F3}. This is \QD's default mode.

        \row
            \li  \inlineimage designer-connection-tool.png {\QD connection tool icon}
            \li  In \l{Qt Widgets Designer's Signals and Slots Editing Mode}
                {Signals and Slots} mode, we can connect widgets together using
                Qt's signals and slots mechanism. To switch to this mode, press
                \key{F4}.

        \row
            \li  \inlineimage designer-buddy-tool.png {\QD buddy tool icon}
            \li  In \l{Qt Widgets Designer's Buddy Editing Mode}{Buddy Editing Mode},
                buddy widgets can be assigned to label widgets to help them
                handle keyboard focus correctly.

        \row
            \li  \inlineimage designer-tab-order-tool.png {\QD tab order tool icon}
            \li  In \l{Qt Widgets Designer's Tab Order Editing Mode}
                {Tab Order Editing Mode}, we can set the order in which widgets
                receive the keyboard focus.
    \endtable

*/


/*!
    \page designer-widget-mode.html
    \previouspage Qt Widgets Designer's Editing Modes
    \nextpage Qt Widgets Designer's Signals and Slots Editing Mode

    \title Qt Widgets Designer's Widget Editing Mode

    \image designer-editing-mode.png {Screenshot showing the \QD editing
           mode, to change size or position of a component in a layout}

    In the Widget Editing Mode, objects can be dragged from the main window's
    widget box to a form, edited, resized, dragged around on the form, and even
    dragged between forms. Object properties can be modified interactively, so
    that changes can be seen immediately. The editing interface is intuitive
    for simple operations, yet it still supports Qt's powerful layout
    facilities.


    To create and edit new forms, open the \gui File menu and select
    \gui{New Form...} or press \key{Ctrl+N}. Existing forms can also be edited
    by selecting \gui{Open Form...} from the \gui File menu or pressing
    \key{Ctrl+O}.

    At any point, you can save your form by selecting the \gui{Save From As...}
    option from the \gui File menu. The UI files saved by \QD contain
    information about the objects used, and any details of signal and slot
    connections between them.


    \section1 Editing A Form

    By default, new forms are opened in widget editing mode. To switch to Edit
    mode from another mode, select \gui{Edit Widgets} from the \gui Edit menu
    or press the \key F3 key.

    Objects are added to the form by dragging them from the main widget box
    and dropping them in the desired location on the form. Once there, they
    can be moved around simply by dragging them, or using the cursor keys.
    Pressing the \key Ctrl key at the same time moves the selected widget
    pixel by pixel, while using the cursor keys alone make the selected widget
    snap to the grid when it is moved. Objects can be selected by clicking on
    them with the left mouse button. You can also use the \key Tab key to
    change the selection.

    The widget box contains objects in a number of different categories, all of
    which can be placed on the form as required. The only objects that require
    a little more preparation are the \gui Container widgets. These are
    described in further detail in the \l{Using Containers in Qt Widgets Designer}
    chapter.


    \target SelectingObjects
    \table
        \row
            \li  \inlineimage designer-selecting-widget.png {Screenshot showing
                              a widget that is selected in \QD editor mode}
            \li  \b{Selecting Objects}

        Objects on the form are selected by clicking on them with the left
        mouse button. When an object is selected, resize handles are shown at
        each corner and the midpoint of each side, indicating that it can be
        resized.

        To select additional objects, hold down the \key Control key and click on
        them. If more than one object is selected, the current object will be
        displayed with resize handles of a different color.

        To move a widget within a layout, hold down \key Shift and \key Control
        while dragging the widget. This extends the selection to the widget's
        parent layout.

        Alternatively, objects can be selected in the
        \l{The Object Inspector}{Object Inspector}.
    \endtable

    When a widget is selected, normal clipboard operations such as cut, copy,
    and paste can be performed on it. All of these operations can be done and
    undone, as necessary.

    The following shortcuts can be used:

    \target ShortcutsForEditing
    \table
        \header \li Action       \li Shortcut     \li Description
        \row
            \li Cut
            \li \key{Ctrl+X}
            \li Cuts the selected objects to the clipboard.
        \row
            \li Copy
            \li \key{Ctrl+C}
            \li Copies the selected objects to the clipboard.
        \row
            \li Paste
            \li \key{Ctrl+V}
            \li Pastes the objects in the clipboard onto the form.
        \row
            \li Delete
            \li \key Delete
            \li Deletes the selected objects.
        \row
            \li Clone object
            \li \key{Ctrl+drag} (leftmouse button)
            \li Makes a copy of the selected object or group of objects.
        \row
            \li Preview
            \li \key{Ctrl+R}
            \li Shows a preview of the form.
    \endtable

    All of the above actions (apart from cloning) can be accessed via both the
    \gui Edit menu and the form's context menu. These menus also provide
    funcitons for laying out objects as well as a \gui{Select All} function to
    select all the objects on the form.

    Widgets are not unique objects; you can make as many copies of them as you
    need. To quickly duplicate a widget, you can clone it by holding down the
    \key Ctrl key and dragging it. This allows widgets to be copied and placed
    on the form more quickly than with clipboard operations.


    \target DragAndDrop
    \table
        \row
            \li \inlineimage designer-dragging-onto-form.png {Screenshot showing
                             widgets in the ui editor that can be moved freely
                             by using drag and drop}
            \li \b{Drag and Drop}

        \QD makes extensive use of the drag and drop facilities provided by Qt.
        Widgets can be dragged from the widget box and dropped onto the form.

        Widgets can also be "cloned" on the form: Holding down \key Ctrl and
        dragging the widget creates a copy of the widget that can be dragged to
        a new position.

        It is also possible to drop Widgets onto the \l {The Object Inspector}
        {Object Inspector} to handle nested layouts easily.
    \endtable

    \QD allows selections of objects to be copied, pasted, and dragged between
    forms. You can use this feature to create more than one copy of the same
    form, and experiment with different layouts in each of them.


    \section2 The Property Editor

    The Property Editor always displays properties of the currently selected
    object on the form. The available properties depend on the object being
    edited, but all of the widgets provided have common properties such as
    \l{QObject::}{objectName}, the object's internal name, and
    \l{QWidget::}{enabled}, the property that determines whether an
    object can be interacted with or not.


    \target EditingProperties
    \table
        \row
            \li \inlineimage designer-property-editor.png {Screenshot showing
                             the property editor of a widget with options to
                             freely change the widget as desired}
            \li \b{Editing Properties}

        The property editor uses standard Qt input widgets to manage the
        properties of objects on the form. Textual properties are shown in line
        edits, integer properties are displayed in spinboxes, boolean
        properties are displayed in check boxes, and compound properties such
        as colors and sizes are presented in drop-down lists of input widgets.

        Modified properties are indicated with bold labels. To reset them, click
        the arrow button on the right.

        Changes in properties are applied to all selected objects that have the
        same property.
    \endtable

    Certain properties are treated specially by the property editor:

    \list
        \li Compound properties -- properties that are made up of more than one
           value -- are represented as nodes that can be expanded, allowing
           their values to be edited.
        \li Properties that contain a choice or selection of flags are edited
           via combo boxes with checkable items.
        \li Properties that allow access to rich data types, such as QPalette,
           are modified using dialogs that open when the properties are edited.
           QLabel and the widgets in the \gui Buttons section of the widget box
           have a \c text property that can also be edited by double-clicking
           on the widget or by pressing \gui F2. \QD interprets the backslash
           (\\) character specially, enabling newline (\\n) characters to be
           inserted into the text; the \\\\ character sequence is used to
           insert a single backslash into the text. A context menu can also be
           opened while editing, providing another way to insert special
           characters and newlines into the text.
    \endlist


    \section2 Dynamic Properties

    The property editor can also be used to add new
    \l{QObject#Dynamic Properties}{dynamic properties} to both standard Qt
    widgets and to forms themselves. Since Qt 4.4, dynamic properties are added
    and removed via the property editor's toolbar, shown below.

    \image designer-property-editor-toolbar.png {Screenshot showing the property
           editor toolbar for a widget}

    To add a dynamic property, click on the \gui Add button
    \inlineimage designer-property-editor-add-dynamic.png {Add button}
    . To remove it, click on the \gui Remove button
    \inlineimage designer-property-editor-remove-dynamic.png {Remove button}
     instead. You can also sort the properties alphabetically and change the
    color groups by clickinig on the \gui Configure button
    \inlineimage designer-property-editor-configure.png {Configure button}
    .

    \section2 The Object Inspector
    \table
        \row
            \li  \inlineimage designer-object-inspector.png {Screenshot showing
                              an object tree of all widgets in the layout}
            \li  \b{The Object Inspector}

        The \gui{Object Inspector} displays a hierarchical list of all the
        objects on the form that is currently being edited. To show the child
        objects of a container widget or a layout, click the handle next to the
        object label.

        Each object on a form can be selected by clicking on the corresponding
        item in the \gui{Object Inspector}. Right-clicking opens the form's
        context menu. These features can be useful if you have many overlapping
        objects. To locate an object in the \gui{Object Inspector}, use
        \key{Ctrl+F}.

        Since Qt 4.4, double-clicking on the object's name allows you to change
        the object's name with the in-place editor.

        Since Qt 4.5, the \gui{Object Inspector} displays the layout state of
        the containers. The broken layout icon ###ICON is displayed if there is
        something wrong with the layouts.

    \endtable
*/


/*!
    \page designer-layouts.html
    \previouspage Qt Widgets Designer's Widget Editing Mode
    \nextpage Qt Widgets Designer's Signals and Slots Editing Mode

    \title Using Layouts in Qt Widgets Designer

    Before a form can be used, the objects on the form need to be placed into
    layouts. This ensures that the objects will be displayed properly when the
    form is previewed or used in an application. Placing objects in a layout
    also ensures that they will be resized correctly when the form is resized.

    Once widgets have been inserted into a layout, it is not possible to move
    and resize them individually because the layout itself controls the
    geometry of each widget within it, taking account of the hints provided by
    spacers. Spacers can be added to the layout to influence the geometries of
    the widgets.

    Layouts can be nested to form a hierarchy. For example, to achieve a
    typical dialog layout with a horizontal row of buttons, the dialog
    elements can be laid out using a vertical box layout with a horizontal
    box layout containing the buttons at the bottom. For an introduction to
    the Qt layout system, refer to \l{Layout Management}.

    To break a layout, press \key{Ctrl+0} or choose \gui{Break Layout} from
    the form's context menu, the \gui Form menu or the main toolbar.

    \section1 Setting A Top Level Layout

    The form's top level layout can be set by clearing the selection (click the
    left mouse button on the form itself) and applying a layout. A top level
    layout is necessary to ensure that your widgets will resize correctly when
    its window is resized. To check if you have set a top level layout, preview
    your widget and attempt to resize the window by dragging the size grip.

    \table
        \row
            \li  \inlineimage designer-set-layout.png {Screenshot showing buttons
                              to change the layout type}
            \li  \b{Applying a Layout}

        To apply a layout, you can select your choice of layout from the
        toolbar shown on the left, or from the context menu shown below.
    \endtable

    Similary, top level layouts are set on container widgets (QGroupBox)
    or on pages of page-based container widgets (QTabWidget, QToolBox
    and QStackedWidget), respectively. The container widget needs to be
    selected for this to succeed.

    Top level layouts are not visible as separate objects in the Object
    Inspector. Their properties appear below the widget properties of the
    main form, container widget, or page of a container widget in the
    Property Editor.

    \image designer-set-layout2.png {Screenshot showing another option
           to change layout type by right clicking in the editor}


    \section1 Layout Objects

    Layout objects are created by applying a layout to a group of
    existing objects. This is achieved by selecting the objects that you need
    to manage and applying one of the standard layouts using the main toolbar,
    the \gui Form menu, or the form's context menu.

    The layout object is indicated by a red frame on the form and appears as
    an object in the Object Inspector. Its properties (margins and constraints)
    are shown in the Property Editor.

    The layout object can be selected and placed within another layout along
    with other widgets and layout objects to build a layout hierarchy.

    When a child layout object is selected, its parent layout object can be
    selected by pressing down the \key Shift key while clicking on it. This
    makes it possible to select a specific layout in a hierarchy, which is
    otherwise difficult due to the small frame.


    \section1 Inserting Objects Into a Layout
    \target InsertingObjectsIntoALayout

    Objects can be inserted into an existing layout by dragging them from
    their current positions and dropping them at the required location. A
    blue cursor is displayed in the layout as an object is dragged over
    it to indicate where the object will be added.

     \image designer-layout-inserting.png {Screenshot showing how to move
            widgets in a layout with drag and drop}
     \caption Inserting Objects into a Layout

    \section1 Layout Types
    \section2 Horizontal and Vertical (Box) Layouts

    The simplest way to arrange objects on a form is to place them in a
    horizontal or vertical layout. Horizontal layouts ensure that the widgets
    within are aligned horizontally; vertical layouts ensure that they are
    aligned vertically.

    Horizontal and vertical layouts can be combined and nested to any depth.
    However, if you need more control over the placement of objects, consider
    using the grid layout.


    \section2 The Grid Layout

    Complex form layouts can be created by placing objects in a grid layout.
    This kind of layout gives the form designer much more freedom to arrange
    widgets on the form, but can result in a much less flexible layout.
    However, for some kinds of form layout, a grid arrangement is much more
    suitable than a nested arrangement of horizontal and vertical layouts.


    \section2 The Form Layout

    The QFormLayout
    class manages widgets in a two-column form; the left column holds labels
    and the right column holds field widgets such as line edits, spin boxes,
    etc. The QFormLayout class adheres to various platform look and feel
    guidelines and supports wrapping for long rows.

    \image designer-form-layout.png {Screenshot showing a layout example with
           two labels and on each label a text field on the side}

    The UI file above results in the previews shown below.

    \table
        \header
            \li  Windows
            \li  \macos
            \li  Cleanlooks
        \row
            \li  \inlineimage designer-form-layout-windows.webp {Screenshot
                              showing the layout preview on Windows}
            \li  \inlineimage designer-form-layout-macintosh.png {Screenshot
                              showing the layout preview on \macos}
            \li  \inlineimage designer-form-layout-cleanlooks.png {Screenshot
                              showing the layout preview with clean looks on
                              Windows XP}
    \endtable


    \section2 Splitter Layouts

    Another common way to manage the layout of objects on a form is to place
    them in a splitter. These splitters arrange the objects horizontally or
    vertically in the same way as normal layouts, but also allow the user to
    adjust the amount of space allocated to each object.

    \image designer-splitter-layout.png {Screenshot showing to change layout
           to "Lay Out Vertically in Splitter"}

    Although QSplitter is a container widget, \QD treats splitter objects as
    layouts that are applied to existing widgets. To place a group of widgets
    into a splitter, select them
    \l{Qt Widgets Designer's Widget Editing Mode#SelectingObjects}{as described here}
    then apply the splitter layout by using the appropriate toolbar button,
    keyboard shortcut, or \gui{Lay out} context menu entry.


    \section1 Shortcut Keys

    In addition to the standard toolbar and context menu entries, there is also
    a set of keyboard shortcuts to apply layouts on widgets.

    \target LayoutShortcuts
    \table
        \header
            \li  Layout
            \li  Shortcut
            \li  Description
        \row
            \li  Horizontal
            \li  \key{Ctrl+1}
            \li  Places the selected objects in a horizontal layout.
        \row
            \li  Vertical
            \li  \key{Ctrl+2}
            \li  Places the selected objects in a vertical layout.
        \row
            \li  Grid
            \li  \key{Ctrl+5}
            \li  Places the selected objects in a grid layout.
        \row
            \li  Form
            \li  \key{Ctrl+6}
            \li  Places the selected objects in a form layout.
        \row
            \li  Horizontal splitter
            \li  \key{Ctrl+3}
            \li  Creates a horizontal splitter and places the selected objects
                inside it.
        \row
            \li  Vertical splitter
            \li  \key{Ctrl+4}
            \li  Creates a vertical splitter and places the selected objects
                inside it.
        \row
            \li  Adjust size
            \li  \key{Ctrl+J}
            \li  Adjusts the size of the layout to ensure that each child object
                has sufficient space to display its contents. See
                QWidget::adjustSize() for more information.
    \endtable

    \note \key{Ctrl+0} is used to break a layout.

*/


/*!
    \page designer-preview.html
    \previouspage Using Layouts in Qt Widgets Designer
    \nextpage Qt Widgets Designer's Buddy Editing Mode
    \title Saving, Previewing and Printing Forms in Qt Widgets Designer

    Although \QD's forms are accurate representations of the components being
    edited, it is useful to preview the final appearance while editing. This
    feature can be activated by opening the \gui Form menu and selecting
    \gui Preview, or by pressing \key{Ctrl+R} when in the form.

    \image designer-dialog-preview.png {Screenshot showing a preview of a layout
           to create an image with options to change name, width, height, and
           color depth}

    The preview shows exactly what the final component will look like when used
    in an application.

    Since Qt 4.4, it is possible to preview forms with various skins - default
    skins, skins created with Qt Style Sheets or device skins. This feature
    simulates the effect of calling \c{QApplication::setStyleSheet()} in the
    application.

    To preview your form with skins, open the \gui Edit menu and select
    \gui{Preferences...}

    You will see the dialog shown below:

    \image designer-preview-style.png {Screenshot of preferences dialog showing
           options for interface mode, font settings, print and preview
           configuration, additional template paths, and grid visibility
           and snapping}

    The \gui{Print/Preview Configuration} checkbox must be checked to activate
    previews of skins. You can select the styles provided from the \gui{Style}
    drop-down box.

    \image designer-preview-style-selection.png {Screenshot of \QD print
           and preview configuration section showing a dropdown menu for selecting
           interface styles, including Default, Windows, WindowsXP etc.}

    Alternatively, you can preview custom style sheet created with Qt Style
    Sheets. The figure below shows an example of Qt Style Sheet syntax and the
    corresponding output.

    \image designer-preview-stylesheet.png {Screenshot of \QD dialogs
           showing the Edit Style Sheet window with QLineEdit CSS properties
           and the Create Image dialog for defining image name, size, and color
           depth}

    Another option would be to preview your form with device skins. A list of
    generic device skins are available in \QD, however, you may also use
    other QVFB skins with the \gui{Browse...} option.

    \image designer-preview-deviceskin-selection.png {Screenshot of \QD
           print and preview configuration showing a dropdown menu for selecting
           device skins}


    \section1 Viewing the Form's Code

    Since Qt 4.4, it is possible to view code generated by the User Interface
    Compiler (uic) for the \QD form.

    \image designer-form-viewcode.png {Screenshot showing option to view
           the layout in code under the drop down menu of "Forms"}

    Select \gui{View Code...} from the \gui{Form} menu and a dialog with the
    generated code will be displayed. The screenshot below is an example of
    code generated by the \c{uic}.

    \image designer-code-viewer.png {Screenshot showing a code of "Form" in a
           code viewer}

    \section1 Saving and Printing the Form

    Forms created in \QD can be saved to an image or printed.

    \table
    \row
    \li \inlineimage designer-file-menu.png {Screenshot showing file menu options}
    \li \b{Saving Forms}

    To save a form as an image, choose the \gui{Save Image...} option. The file
    will be saved in \c{.png} format.

    \b{Printing Forms}

    To print a form, select the \gui{Print...} option.

    \endtable
*/


/*!
    \page designer-connection-mode.html
    \previouspage Using Layouts in Qt Widgets Designer
    \nextpage Qt Widgets Designer's Buddy Editing Mode


    \title Qt Widgets Designer's Signals and Slots Editing Mode

    \image designer-connection-mode.png {Screenshot of \QD connection mode
           showing the connection of signals between two widgets}

    In \QD's signals and slots editing mode, you can connect objects in a form
    together using Qt's signals and slots mechanism. Both widgets and layouts
    can be connected via an intuitive connection interface, using the menu of
    compatible signals and slots provided by \QD. When a form is saved, all
    connections are preserved so that they will be ready for use when your
    project is built.


    For more information on Qt's signals and sltos mechanism, refer to the
    \l{Signals and Slots} document.


    \section1 Connecting Objects

    To begin connecting objects, enter the signals and slots editing mode by
    opening the \gui Edit menu and selecting \gui{Edit Signals/Slots}, or by
    pressing the \key F4 key.

    All widgets and layouts on the form can be connected together. However,
    spacers just provide spacing hints to layouts, so they cannot be connected
    to other objects.


    \target HighlightedObjects
    \table
        \row
            \li  \inlineimage designer-connection-highlight.png {Screenshot
                              showing a widget of a layout that is highlighted}
            \li  \b{Highlighted Objects}

        When the cursor is over an object that can be used in a connection, the
        object will be highlighted.
    \endtable

    To make a connectionn, press the left mouse button and drag the cursor
    towards the object you want to connect it to. As you do this, a line will
    extend from the source object to the cursor. If the cursor is over another
    object on the form, the line will end with an arrow head that points to the
    destination object. This indicates that a connection will be made between
    the two objects when you release the mouse button.

    You can abandon the connection at any point while you are dragging the
    connection path by pressing \key{Esc}.

    \target MakingAConnection
    \table
        \row
            \li  \inlineimage designer-connection-making.png {Screenshot showin
                              how to connect one widget to another by pressing
                              left click to the desired widget that should be
                              connected to}
            \li  \b{Making a Connection}

        The connection path will change its shape as the cursor moves around
        the form. As it passes over objects, they are highlighted, indicating
        that they can be used in a signal and slot connection. Release the
        mouse button to make the connection.
    \endtable

    The \gui{Configure Connection} dialog (below) is displayed, showing signals
    from the source object and slots from the destination object that you can
    use.

    \image designer-connection-dialog.png {Screenshot of window listing signals
           that can be emitted between two selected widgets}

    To complete the connection, select a signal from the source object and a
    slot from the destination object, then click \key OK. Click \key Cancel if
    you wish to abandon the connection.

    \note If the \gui{Show all signals and slots} checkbox is selected, all
    available signals from the source object will be shown. Otherwise, the
    signals and slots inherited from QWidget will be hidden.

    You can make as many connections as you like between objects on the form;
    it is possible to connect signals from objects to slots in the form itself.
    As a result, the signal and slot connections in many dialogs can be
    completely configured from within \QD.

    \target ConnectingToTheForm
    \table
        \row
            \li  \inlineimage designer-connection-to-form.png {Screenshot showing
                              an arrow coming from a widget following the cursor
                              to choose a widget that receives the signals}
            \li  \b{Connecting to a Form}

        To connect an object to the form itself, simply position the cursor
        over the form and release the mouse button. The end point of the
        connection changes to the electrical "ground" symbol.
    \endtable


    \section1 Editing and Deleting Connections

    By default, connection paths are created with two labels that show the
    signal and slot involved in the connection. These labels are usually
    oriented along the line of the connection. You can move them around inside
    their host widgets by dragging the red square at each end of the connection
    path.

    \target ConnectionEditor
    \table
        \row
            \li  \inlineimage designer-connection-editor.png {Screenshot of Qt
                              Designer Signal and Slot editor showing connections
                              between an okButton and a cancelButton where the
                              okButton and cancelbutton send a "clicked()" signal.
                              The okButton triggers the "accept()" function and
                              the cancelButton "reject()"}
            \li  \b{The Signal/Slot Editor}

        The signal and slot used in a connection can be changed after it has
        been set up. When a connection is configured, it becomes visible in
        \QD's signal and slot editor where it can be further edited. You can
        also edit signal/slot connections by double-clicking on the connection
        path or one of its labels to display the Connection Dialog.
    \endtable

    \target DeletingConnections
    \table
        \row
            \li  \inlineimage designer-connection-editing.png {Screenshot
                              showing connection edit mode to change the
                              signals between two widgets}
            \li  \b{Deleting Connections}

        The whole connection can be selected by clicking on any of its path
        segments. Once selected, a connection can be deleted with the
        \key Delete key, ensuring that it will not be set up in the UI
        file.
    \endtable
*/


/*!
    \page designer-buddy-mode.html
    \previouspage Qt Widgets Designer's Signals and Slots Editing Mode
    \nextpage Qt Widgets Designer's Tab Order Editing Mode

    \title Qt Widgets Designer's Buddy Editing Mode

    \image designer-buddy-mode.png {Screenshot of buddy mode showing which widget
           are bindet together}

    One of the most useful basic features of Qt is the support for buddy
    widgets. A buddy widget accepts the input focus on behalf of a QLabel when
    the user types the label's shortcut key combination. The buddy concept is
    also used in Qt's \l{Model/View Programming}{model/view} framework.


    \section1 Linking Labels to Buddy Widgets

    To enter buddy editing mode, open the \gui Edit menu and select
    \gui{Edit Buddies}. This mode presents the widgets on the form in a similar
    way to \l{Qt Widgets Designer's Signals and Slots Editing Mode}{signals and slots
    editing mode} but in this mode, connections must start at label widgets.
    Ideally, you should connect each label widget that provides a shortcut with
    a suitable input widget, such as a QLineEdit.


    \target MakingBuddies
    \table
        \row
            \li  \inlineimage designer-buddy-making.png {Screenshot showing how to
                              bind widgets by pressing on one widget and move the
                              cursor to the other widget that should be bindet to}
            \li  \b{Making Buddies}

        To define a buddy widget for a label, click on the label, drag the
        connection to another widget on the form, and release the mouse button.
        The connection shown indicates how input focus is passed to the buddy
        widget. You can use the form preview to test the connections between
        each label and its buddy.
    \endtable


    \section1 Removing Buddy Connections

    Only one buddy widget can be defined for each label. To change the buddy
    used, it is necessary to delete any existing buddy connection before you
    create a new one.

    Connections between labels and their buddy widgets can be deleted in the
    same way as signal-slot connections in signals and slots editing mode:
    Select the buddy connection by clicking on it and press the \key Delete
    key. This operation does not modify either the label or its buddy in any
    way.
*/


/*!
    \page designer-tab-order.html
    \previouspage Qt Widgets Designer's Buddy Editing Mode
    \nextpage Using Containers in Qt Widgets Designer

    \title Qt Widgets Designer's Tab Order Editing Mode

    \image designer-tab-order-mode.png {Screenshot showing the order of the
           layout highlighting in which order the sections of the application
           should be used}

    Many users expect to be able to navigate between widgets and controls
    using only the keyboard. Qt lets the user navigate between input widgets
    with the \key Tab and \key{Shift+Tab} keyboard shortcuts. The default
    \e{tab order} is based on the order in which widgets are constructed.
    Although this order may be sufficient for many users, it is often better
    to explicitly specify the tab order to make your application easier to
    use.


    \section1 Setting the Tab Order

    To enter tab order editing mode, open the \gui Edit menu and select
    \gui{Edit Tab Order}. In this mode, each input widget in the form is shown
    with a number indicating its position in the tab order. So, if the user
    gives the first input widget the input focus and then presses the tab key,
    the focus will move to the second input widget, and so on.

    The tab order is defined by clicking on each of the numbers in the correct
    order. The first number you click will change to red, indicating the
    currently edited position in the tab order chain. The widget associated
    with the number will become the first one in the tab order chain. Clicking
    on another widget will make it the second in the tab order, and so on.

    Repeat this process until you are satisfied with the tab order in the form
    -- you do not need to click every input widget if you see that the
    remaining widgets are already in the correct order. Numbers, for which you
    already set the order, change to green, while those which are not clicked
    yet, remain blue.

    If you make a mistake, simply double click outside of any number or choose
    \gui{Restart} from the form's context menu to start again. If you have many
    widgets on your form and would like to change the tab order in the middle or
    at the end of the tab order chain, you can edit it at any position. Press
    \key{Ctrl} and click the number from which you want to start.
    Alternatively, choose \gui{Start from Here} in the context menu.

*/


/*!
    \page designer-using-containers.html
    \previouspage Qt Widgets Designer's Tab Order Editing Mode
    \nextpage Creating Main Windows in Qt Widgets Designer


    \title Using Containers in Qt Widgets Designer

    Container widgets provide high level control over groups of objects on a
    form. They can be used to perform a variety of functions, such as managing
    input widgets, providing paged and tabbed layouts, or just acting as
    decorative containers for other objects.

    \image designer-widget-morph.png {Screenshot showing the "Morph into" options
           for a button. It shows option to morph into QCheckbox, QRadioButton,
           QToolButton, and QCommandLinkButton}

    \QD provides visual feedback to help you place objects inside your
    containers. When you drag an object from the widget box (or elsewhere) on
    the form, each container will be highlighted when the cursor is positioned
    over it. This indicates that you can drop the object inside, making it a
    child object of the container. This feedback is important because it is
    easy to place objects close to containers without actually placing them
    inside. Both widgets and spacers can be used inside containers.

    Stacked widgets, tab widgets, and toolboxes are handled specially in \QD.
    Normally, when adding pages (tabs, pages, compartments) to these containers
    in your own code, you need to supply existing widgets, either as
    placeholders or containing child widgets. In \QD, these are automatically
    created for you, so you can add child objects to each page straight away.

    Each container typically allows its child objects to be arranged in one or
    more layouts. The type of layout management provided depends on each
    container, although setting the layout is usually just a matter of
    selecting the container by clicking it, and applying a layout. The table
    below shows a list of available containers.

    \table
        \row
            \li  \inlineimage designer-containers-frame.png {Screenshot showing
                              a frame that is selected}
            \li  \b Frames

        Frames are used to enclose and group widgets, as well as to provide
        decoration. They are used as the foundation for more complex
        containers, but they can also be used as placeholders in forms.

        The most important properties of frames are \c frameShape,
        \c frameShadow, \c lineWidth, and \c midLineWidth. These are described
        in more detail in the QFrame class description.

        \row
            \li  \inlineimage designer-containers-groupbox.png {Screenshot
                              showing a group box, including multiple widgets,
                              that is selected}
            \li  \b{Group Boxes}

        Group boxes are usually used to group together collections of
        checkboxes and radio buttons with similar purposes.

        Among the significant properties of group boxes are \c title, \c flat,
        \c checkable, and \c checked, as described in the \l QGroupBox
        class documentation. Each group box can contain its own layout, and
        this is necessary if it contains other widgets. To add a layout to the
        group box, click inside it and apply the layout as usual.

        \row
            \li  \inlineimage designer-containers-stackedwidget.png {Screenshot
                              showing group box containing widgets that are
                              stacked on on of each other}
            \li  \b{Stacked Widgets}

        Stacked widgets are collections of widgets in which only the topmost
        layer is visible. Control over the visible layer is usually managed by
        another widget, such as combobox, using signals and slots.

        \QD shows arrows in the top-right corner of the stack to allow you to
        see all the widgets in the stack when designing it. These arrows do not
        appear in the preview or in the final component. To navigate between
        pages in the stack, select the stacked widget and use the
        \gui{Next Page} and \gui{Previous Page} entries from the context menu.
        The \gui{Insert Page} and \gui{Delete Page} context menu options allow
        you to add and remove pages.

        \row
            \li  \inlineimage designer-containers-tabwidget.png {Screenshot showing
                              a tab widget in a container}
            \li  \b{Tab Widgets}

        Tab widgets allow the developer to split up the contents of a widget
        into different labelled sections, only one of which is displayed at any
        given time. By default, the tab widget contains two tabs, and these can
        be deleted or renamed as required. You can also add additional tabs.

        To delete a tab:
        \list
            \li  Click on its label to make it the current tab.
            \li  Select the tab widget and open its context menu.
            \li  Select \gui{Delete Page}.
        \endlist

        To add a new tab:
        \list
            \li  Select the tab widget and open its context menu.
            \li  Select \gui{Insert Page}.
            \li  You can add a page before or after the \e current page. \QD
                will create a new widget for that particular tab and insert it
                into the tab widget.
            \li  You can set the title of the current tab by changing the
                \c currentTabText property in the \gui{Property Editor}.
        \endlist

        \row
            \li  \inlineimage designer-containers-toolbox.png {Screensshot showing
                              a toolbox in a container}
            \li  \b{ToolBox Widgets}

        Toolbox widgets provide a series of pages or compartments in a toolbox.
        They are handled in a way similar to stacked widgets.

        To rename a page in a toolbox, make the toolbox your current pange and
        change its \c currentItemText property from the \gui{Property Editor}.

        To add a new page, select \gui{Insert Page} from the toolbox widget's
        context menu. You can add the page before or after the current page.

        To delete a page, select \gui{Delete Page} from the toolbox widget's
        context menu.

        \row
            \li  \inlineimage designer-containers-dockwidget.png {Screenshot
                              showing a dock widget in a container}
            \li  \b{Dock Widgets}

        Dock widgets are floating panels, often containing input widgets and
        more complex controls, that are either attached to the edges of the
        main window in "dock areas", or floated as independent tool windows.

        Although dock widgets can be added to any type of form, they are
        typically used with forms created from the
        \l{Creating Main Windows in Qt Widgets Designer}{main window template}.

    \endtable
*/


/*!
    \page designer-creating-mainwindows.html
    \previouspage Using Containers in Qt Widgets Designer
    \nextpage Editing Resources with Qt Widgets Designer

    \title Creating Main Windows in Qt Widgets Designer

    \QD can be used to create user interfaces for different purposes, and
    it provides different kinds of form templates for each user interface. The
    main window template is used to create application windows with menu bars,
    toolbars, and dock widgets.

    \omit
    \image designer-mainwindow-example.png
    \endomit

    Create a new main window by opening the \gui File menu and selecting the
    \gui{New Form...} option, or by pressing \key{Ctrl+N}. Then, select the
    \gui{Main Window} template. This template provides a main application
    window containing a menu bar and a toolbar by default -- these can be
    removed if they are not required.

    If you remove the menu bar, a new one can be created by selecting the
    \gui{Create Menu Bar} option from the context menu, obtained by
    right-clicking within the main window form.

    An application can have only \b one menu bar, but \b several
    toolbars.


    \section1 Menus

    Menus are added to the menu bar by modifying the \gui{Type Here}
    placeholders. One of these is always present for editing purposes, and
    will not be displayed in the preview or in the finished window.

    Once created, the properties of a menu can be accessed using the
    \l{Qt Widgets Designer's Widget Editing Mode#The Property Editor}{Property Editor},
    and each menu can be accessed for this purpose via the
    \l{Qt Widgets Designer's Widget Editing Mode#The Object Inspector}{The Object Inspector}.

    Existing menus can be removed by opening a context menu over the label in
    the menu bar, and selecting \gui{Remove Menu 'menu_name'}.


    \target CreatingAMenu
    \div {class="float-left"}
    \inlineimage designer-creating-menu1.png {Screenshot showing cursor hovering over a
                 button to create a menu on the window}
    \inlineimage designer-creating-menu2.png {Screenshot showing cursor clicking on the
                 button to create a menu on the window}
    \br
    \inlineimage designer-creating-menu3.png {Screenshot showing a text field that
                 results when clicking the button to name the menu}
    \inlineimage designer-creating-menu4.png {Screenshot showing the newly created menu}
    \enddiv

    \section2 Creating a Menu

    Double-click the placeholder item to begin editing. The menu text,
    displayed using a line edit, can be modified.

    Insert the required text for the new menu. Inserting an
    ampersand character (&) causes the letter following it to be
    used as a mnemonic for the menu.

    Press \key Return or \key Enter to accept the new text, or press
    \key Escape to reject it. You can undo the editing operation later if
    required.

    \div {class="clear-both"}
    \enddiv

    Menus can also be rearranged in the menu bar simply by dragging and
    dropping them in the preferred location. A vertical red line indicates the
    position where the menu will be inserted.

    Menus can contain any number of entries and separators, and can be nested
    to the required depth. Adding new entries to menus can be achieved by
    navigating the menu structure in the usual way.

    \target CreatingAMenuEntry
    \div {class="float-right"}
    \inlineimage designer-creating-menu-entry1.png {Screenshot of cursor
                 clicking on the new menu showing a dropdown menu with
                 button to create options or separators to the dropdown
                 menu}
    \inlineimage designer-creating-menu-entry2.png {Screenshot of cursor
                 clicking on button to add option to the dropdown menu by
                 writing a name in the textfield}
    \br
    \inlineimage designer-creating-menu-entry3.png {Screenshot showing the
                 newly created button on the dropdown menu}
    \inlineimage designer-creating-menu-entry4.png {Screehsot of cursor
                 clicking the button showing an option to create another
                 button that pops up after clicking}
    \enddiv

    \section2 Creating a Menu Entry

    Double-click the \gui{Type Here} placeholder to begin editing, or
    double-click \gui{Add Separator} to insert a new separator line after
    the last entry in the menu.

    The menu entry's text is displayed using a line edit, and can be
    modified.

    Insert the required text for the new entry, optionally using
    the ampersand character (&) to mark the letter to use as a
    mnemonic for the entry.

    Press \key Return or \key Enter to accept the new text, or press
    \key Escape to reject it. The action created for this menu entry will
    be accessible via the \l{#TheActionEditor}{Action Editor}, and any
    associated keyboard shortcut can be set there.

    \div {class="clear-both"}
    \enddiv

    Just like with menus, entries can be moved around simply by dragging and
    dropping them in the preferred location. When an entry is dragged over a
    closed menu, the menu will open to allow it to be inserted there. Since
    menu entries are based on actions, they can also be dropped onto toolbars,
    where they will be displayed as toolbar buttons.

    \section1 Toolbars

    \div {class="float-left"}
    \inlineimage designer-creating-toolbar.png {Screenshot showing option to
                 add a tool bar by right clicking on the ui editor}
    \enddiv

    \section2 Creating and Removing a Toolbar

    Toolbars are added to a main window in a similar way to the menu bar:
    Select the \gui{Add Tool Bar} option from the form's context menu.
    Alternatively, if there is an existing toolbar in the main window, you can
    click the arrow on its right end to create a new toolbar.

    Toolbars are removed from the form via an entry in the toolbar's context
    menu.

    \div {class="clear-both"}
    \enddiv

    \section2 Adding and Removing Toolbar Buttons

    Toolbar buttons are created as actions in the
    \l{#TheActionEditor}{Action Editor} and dragged onto the toolbar.
    Since actions can be represented by menu entries and toolbar buttons,
    they can be moved between menus and toolbars.

    \div {class="float-right"}
    \inlineimage designer-adding-toolbar-action.png {Screenshot showing cursor
                 adding a toolbar with drag and drop}
    \inlineimage designer-removing-toolbar-action.png {Screenshot showing option
                 to remove toolbar by right clicking on it}
    \enddiv

    To share an action between a menu and a toolbar, drag its icon from the
    action editor to the toolbar rather than from the menu where its entry is
    located. See \l{#Adding an Action}{Adding an Action} for more information
    about this process.

    Toolbar buttons are removed via the toolbar's context menu.

    \div {class="clear-both"}
    \enddiv

    \section1 Actions

    With the menu bar and the toolbars in place, it's time to populate them
    with actions. New actions for both menus and toolbars are created in the
    action editor window, simplifying the creation and management of actions.

    \target TheActionEditor
    \div {class="float-left"}
    \inlineimage designer-action-editor.png {Screenshot of action editor
                 listing all actions of a toolbar}
    \enddiv

    \section2 The Action Editor

    Enable the action editor by opening the \gui Tools menu, and switching
    on the \gui{Action Editor} option.

    The action editor allows you to create \gui New actions and \gui Delete
    actions. It also provides a search function, \gui Filter, using the
    action's text.

    \QD's action editor can be viewed in the classic \gui{Icon View} and
    \gui{Detailed View}. The screenshot below shows the action editor in
    \gui{Detailed View}. You can also copy and paste actions between menus,
    toolbars and forms.

    \div {class="clear-both"}
    \enddiv

    \section2 Creating an Action

    To create an action, use the action editor's \gui New button, which will
    then pop up an input dialog. Provide the new action with a \gui Text --
    this is the text that will appear in a menu entry and as the action's
    tooltip. The text is also automatically added to an "action" prefix,
    creating the action's \gui{Object Name}.

    In addition, the dialog provides the option of selecting an \gui Icon for
    the action, as well as removing the current icon.

    Once the action is created, it can be used wherever actions are applicable.

    \div {class="clear-left"}
    \enddiv

    \target AddingAnAction
    \div {class="float-right"}
    \inlineimage designer-adding-menu-action.png {Screenshot showing cursor
                 adding a toolbar with drag and drop}
    \inlineimage designer-adding-toolbar-action.png {Screenshot showing option
                 to remove toolbar by right clicking on it}
    \enddiv

    \section2 Adding an Action

    To add an action to a menu or a toolbar, simply press the left mouse
    button over the action in the action editor, and drag it to the
    preferred location.

    \QD provides highlighted guide lines that tell you where the action
    will be added. Release the mouse button to add the action when you have
    found the right spot.

    \div {class="clear-right"}
    \enddiv

    \section1 Dock Widgets

    Dock widgets are \l{Using Containers in Qt Widgets Designer}{container widgets}
    as well. They can be added to a form by dropping them onto the desired
    dock area.

    \target AddingADockWidget

    \div {class="float-left"}
    \inlineimage designer-adding-dockwidget.png {Screenshot showing how to add a
                 dock widget by using drag and drop}
    \enddiv

    \section2 Adding a Dock Widget

    To add a dock widget to a form, drag one from the \gui Containers section
    of the widget box, and drop it onto the main form area. Do not add the
    dock widget to an existing layout. Instead, open the \gui{Property Editor}
    and enable the \gui{docked} property to place it in a dock area.

    Note that it is sometimes easier to configure a dock widget if it is added
    to a form before a layout is applied to the central widget. For example,
    it is possible to undock it and resize it, making it more convenient to
    add child widgets.

    Dock widgets can be optionally floated as independent tool windows.
    Hence, it is useful to give them window titles by setting their
    \l{QDockWidget::}{windowTitle} property. This also helps to identify them on the
    form.

    \div {class="clear-both"}
    \enddiv
*/


/*!
    \page designer-resources.html
    \previouspage Creating Main Windows in Qt Widgets Designer
    \nextpage Using Stylesheets with Qt Widgets Designer

    \title Editing Resources with Qt Widgets Designer

    \image designer-resources-editing.png {Screenshot of Edit Resources
           dialog showing a resource file containing two image entries}

    \QD fully supports the \l{The Qt Resource System}{Qt Resource System},
    enabling resources to be specified together with forms as they are
    designed. To aid designers and developers manage resources for their
    applications, \QD's resource editor allows resources to be defined on a
    per-form basis. In other words, each form can have a separate resource
    file.

    \section1 Defining a Resource File

    To specify a resource file you must enable the resource editor by opening
    the \gui Tools menu, and switching on the \gui{Resource Browser} option.

    \target ResourceFiles
    \table
        \row
            \li  \inlineimage designer-resource-browser.png {Screenshot of the
                              "Resource Browser" window showing the resource
                              root directory}
            \li  \b{Resource Files}

        Within the resource browser, you can open existing resource files or
        create new ones. Click the \gui{Edit Resources} button
        \inlineimage designer-edit-resources-button.png {Edit button}
         to edit your resources. To reload resources, click on the \gui Reload
        button
        \inlineimage designer-reload-resources-button.png {Reload resources
                     button}
        .
    \endtable


    Once a resource file is loaded, you can create or remove entries in it
    using the given \gui{Add Files}
    \inlineimage designer-add-resource-entry-button.png {Add resource entry button}
    and \gui{Remove Files}
    \inlineimage designer-remove-resource-entry-button.png {Remove resource entry button}
     buttons, and specify resources (e.g., images) using the \gui{Add Files}
    button
    \inlineimage designer-add-files-button.png {Add files button}
    . Note that these resources must reside within the current resource file's
    directory or one of its subdirectories.


    \target EditResource
    \table
        \row
            \li  \inlineimage designer-edit-resource.png {Screenshot of Edit Resources
                              dialog showing a resource file with a single prefix entry
                              labeled newPrefix}
            \li  \b{Editing Resource Files}

        Press the
        \inlineimage designer-add-resource-entry-button.png {Add resource entry
                     button}
         button to add a new resource entry to the file. Then use the
        \gui{Add Files} button
        \inlineimage designer-add-files-button.png {Add files button}
         to specify the resource.

        You can remove resources by selecting the corresponding entry in the
        resource editor, and pressing the
        \inlineimage designer-remove-resource-entry-button.png {Remove resource entry
                     button}
         button.
    \endtable


    \section1 Using the Resources

    Once the resources are defined you can use them actively when composing
    your form. For example, you might want to create a tool button using an
    icon specified in the resource file.

    \target UsingResources
    \table
        \row
            \li  \inlineimage designer-resources-using.png {Screenshot of property
                              editor showing the icon property with different states,
                              Normal Off, Normal On and Disabled Off and the option
                              to choose an image resource}
            \li  \b{Using Resources}

        When changing properties with values that may be defined within a
        resource file, \QD's property editor allows you to specify a resource
        in addition to the option of selecting a source file in the ordinary
        way.

        \row
            \li  \inlineimage designer-resource-selector.png {Screenshot of "Select
                              Resource" window showing an option to choose which
                              image should be used as a resource}
            \li  \b{Selecting a Resource}

        You can open the resource selector by clicking \gui{Choose Resource...}
        to add resources any time during the design process.

\omit
... check with Friedemann
To quickly assign icon pixmaps to actions or pixmap properties, you may
drag the pixmap from the resource editor to the action editor, or to the
pixmap property in the property editor.
\endomit

    \endtable
*/


/*!
    \page designer-stylesheet.html
    \previouspage Editing Resources with Qt Widgets Designer
    \nextpage Using a Designer UI File in Your C++ Application

    \title Using Stylesheets with Qt Widgets Designer

    Since Qt 4.2, it is possible to edit stylesheets in \QD with the stylesheet
    editor.

    \target UsingStylesheets
    \table
        \row
            \li \inlineimage designer-stylesheet-options.png {Screenshot of form editor
                             showing a label and line editor with the option
                             highlighted to change stylesheet from the
           context menu}
            \b{Setting a Stylesheet}

            The stylesheet editor can be accessed by right-clicking a widget
            and selecting \gui{Change styleSheet...}

        \row
            \li \inlineimage designer-stylesheet-usage.png {Screenshot showing the
                             preview of used stylesheet}
    \endtable

*/


/*!
    \page designer-using-a-ui-file.html
    \previouspage Using Stylesheets with Qt Widgets Designer
    \nextpage Using a Designer UI File in Your Qt for Python Application

    \keyword Using a Designer UI File in Your Application
    \title Using a Designer UI File in Your C++ Application

    Qt Widgets Designer UI files represent the widget tree of the form in XML format. The
    forms can be processed:

    \list
        \li \l{Compile Time Form Processing}{At compile time}, which means that forms
            are converted to C++ code that can be compiled.
        \li \l{Run Time Form Processing}{At runtime}, which means that forms are processed
            by the QUiLoader class that dynamically constructs the widget tree while
            parsing the XML file.
    \endlist

    \section1 Compile Time Form Processing

    You create user interface components with \QD and use Qt's integrated build tools,
    \l{qmake Manual}{qmake} and \l{User Interface Compiler (uic)}{uic}, to generate code
    for them when the application is built. The generated code contains the form's user
    interface object. It is a C++ struct that contains:

    \list
        \li Pointers to the form's widgets, layouts, layout items,
           button groups, and actions.
        \li A member function called \c setupUi() to build the widget tree
           on the parent widget.
        \li A member function called \c retranslateUi() that handles the
           translation of the string properties of the form. For more information,
           see \l{Reacting to Language Changes}.
    \endlist

    The generated code can be included in your application and used directly from
    it. Alternatively, you can use it to extend subclasses of standard widgets.

    A compile time processed form can be used in your application with one of
    the following approaches:

    \list
        \li  \l{The Direct Approach}: you construct a widget to use as a placeholder
            for the component, and set up the user interface inside it.
        \li  \l{The Single Inheritance Approach}: you subclass the form's base class
            (QWidget or QDialog, for example), and include a private instance
            of the form's user interface object.
        \li  \l{The Multiple Inheritance Approach}: you subclass both the form's base
            class and the form's user interface object. This allows the widgets
            defined in the form to be used directly from within the scope of
            the subclass.
    \endlist

    To demonstrate, we create a simple Calculator Form application. It is based on the
    original \l{Calculator Form} example.

    The application consists of one source file, \c main.cpp and a UI
    file.

    The \c{calculatorform.ui} file designed with \QD is shown below:

    \image directapproach-calculatorform.png {Screenshot of form editor showing a
           calculator layout}

    When using \c CMake to build the executable, a \c{CMakeLists.txt}
    file is required:

    \snippet uitools/calculatorform/CMakeLists.txt 0

    The form is listed among the C++ source files in \c qt_add_executable().
    The option \c CMAKE_AUTOUIC tells \c CMake to run the \c uic tool
    to create a \c ui_calculatorform.h file that can be used
    by the source files.

    When using \c qmake to build the executable, a \c{.pro} file is required:

    \snippet uitools/calculatorform/calculatorform.pro 0

    The special feature of this file is the \c FORMS declaration that tells
    \c qmake which files to process with \c uic. In this case, the
    \c calculatorform.ui file is used to create a \c ui_calculatorform.h file
    that can be used by any file listed in the \c SOURCES declaration.

    \note You can use Qt Creator to create the Calculator Form project. It
    automatically generates the main.cpp, UI, and a project file for the
    desired build tool, which you can modify.

    \section2 The Direct Approach

    To use the direct approach, we include the \c ui_calculatorform.h file
    directly in \c main.cpp:

    \snippet uitools/calculatorform/main.cpp 0

    The \c main function creates the calculator widget by constructing a
    standard QWidget that we use to host the user interface described by the
    \c calculatorform.ui file.

    \snippet uitools/calculatorform/main.cpp 1

    In this case, the \c{Ui::CalculatorForm} is an interface description object
    from the \c ui_calculatorform.h file that sets up all the dialog's widgets
    and the connections between its signals and slots.

    The direct approach provides a quick and easy way to use simple, self-contained
    components in your applications. However, componens created with \QD often
    require close integration with the rest of the application code. For
    instance, the \c CalculatorForm code provided above will compile and run,
    but the QSpinBox objects will not interact with the QLabel as we need a
    custom slot to carry out the add operation and display the result in the
    QLabel. To achieve this, we need to use the single inheritance approach.

    \section2 The Single Inheritance Approach

    To use the single inheritance approach, we subclass a standard Qt widget and
    include a private instance of the form's user interface object. This can take
    the form of:

    \list
        \li A member variable
        \li A pointer member variable
    \endlist

    \section3 Using a Member Variable

    In this approach, we subclass a Qt widget and set up the user interface
    from within the constructor. Components used in this way expose the widgets
    and layouts used in the form to the Qt widget subclass, and provide a
    standard system for making signal and slot connections between the user
    interface and other objects in your application.
    The generated \c{Ui::CalculatorForm} structure is a member of the class.

    This approach is used in the \l{Calculator Form} example.

    To ensure that we can use the user interface, we need to include the header
    file that \c uic generates before referring to \c{Ui::CalculatorForm}:

    \snippet calculatorform/calculatorform.h 0

    The project file must be updated to include \c{calculatorform.h}.
    For \c CMake:

    \snippet calculatorform/CMakeLists.txt 1

    In specific cases, such as the example below where the include directive
    uses a relative path, \l{qt6_add_ui}{qt_add_ui} can be used to generate the
    \c{ui_calculatorform.h} file instead of relying on
    \l{CMake AUTOUIC Documentation}{AUTOUIC}.

    \l{When to prefer qt_add_ui over AUTOUIC}

    \code
        #include "src/files/ui_calculatorform.h"
    \endcode

    \code
        qt_add_ui(calculatorform SOURCES calculatorform.ui
                  INCLUDE_PREFIX src/files)
    \endcode

    For \c qmake:

    \snippet calculatorform/calculatorform.pro 0

    The subclass is defined in the following way:

    \snippet calculatorform/calculatorform.h 1

    The important feature of the class is the private \c ui object which
    provides the code for setting up and managing the user interface.

    The constructor for the subclass constructs and configures all the widgets
    and layouts for the dialog just by calling the \c ui object's \c setupUi()
    function. Once this has been done, it is possible to modify the user
    interface as needed.

    \snippet calculatorform/calculatorform.cpp 0

    We can connect signals and slots in user interface widgets in the usual
    way by adding the on_<object name> - prefix. For more information,
    see \l{widgets-and-dialogs-with-auto-connect}.

    The advantages of this approach are its simple use of inheritance to
    provide a QWidget-based interface, and its encapsulation of the user
    interface widget variables within the \c ui data member. We can use this
    method to define a number of user interfaces within the same widget, each
    of which is contained within its own namespace, and overlay (or compose)
    them. This approach can be used to create individual tabs from existing
    forms, for example.

    \section3 Using a Pointer Member Variable

    Alternatively, the \c{Ui::CalculatorForm} structure can be made a pointer
    member of the class. The header then looks as follows:

    \code

    namespace Ui {
        class CalculatorForm;
    }

    class CalculatorForm : public QWidget
    ...
    virtual ~CalculatorForm();
    ...
    private:
        Ui::CalculatorForm *ui;
    ...

    \endcode

    The corresponding source file looks as follows:

    \code
    #include "ui_calculatorform.h"

    CalculatorForm::CalculatorForm(QWidget *parent) :
        QWidget(parent), ui(new Ui::CalculatorForm)
    {
        ui->setupUi(this);
    }

    CalculatorForm::~CalculatorForm()
    {
        delete ui;
    }
    \endcode

    The advantage of this approach is that the user interface object can be
    forward-declared, which means that we do not have to include the generated
    \c ui_calculatorform.h file in the header. The form can then be changed without
    recompiling the dependent source files. This is particularly important if the
    class is subject to binary compatibility restrictions.

    We generally recommend this approach for libraries and large applications.
    For more information, see \l{Creating Shared Libraries}.

    \section2 The Multiple Inheritance Approach

    Forms created with \QD can be subclassed together with a standard
    QWidget-based class. This approach makes all the user interface components
    defined in the form directly accessible within the scope of the subclass,
    and enables signal and slot connections to be made in the usual way with
    the \l{QObject::connect()}{connect()} function.

    We need to include the header file that \c uic generates from the
    \c calculatorform.ui file, as follows:

    \snippet ../designer/calculatorform_mi/calculatorform.h 0

    The class is defined in a similar way to the one used in the
    \l{The Single Inheritance Approach}{single inheritance approach}, except that
    this time we inherit from \e{both} QWidget and \c{Ui::CalculatorForm},
    as follows:

    \snippet ../designer/calculatorform_mi/calculatorform.h 1

    We inherit \c{Ui::CalculatorForm} privately to ensure that the user
    interface objects are private in our subclass. We can also inherit it with
    the \c public or \c protected keywords in the same way that we could have
    made \c ui public or protected in the previous case.

    The constructor for the subclass performs many of the same tasks as the
    constructor used in the \l{The Single Inheritance Approach}
    {single inheritance} example:

    \snippet ../designer/calculatorform_mi/calculatorform.cpp 0

    In this case, the widgets used in the user interface can be accessed in the
    same say as a widget created in code by hand. We no longer require the
    \c{ui} prefix to access them.

    \section2 Reacting to Language Changes

    Qt notifies applications if the user interface language changes by sending an
    event of the type QEvent::LanguageChange. To call the member function
    \c retranslateUi() of the user interface object, we reimplement
    \c QWidget::changeEvent() in the form class, as follows:

    \code
    void CalculatorForm::changeEvent(QEvent *e)
    {
        QWidget::changeEvent(e);
        switch (e->type()) {
        case QEvent::LanguageChange:
            ui->retranslateUi(this);
            break;
        default:
            break;
       }
    }
    \endcode

    \section1 Run Time Form Processing

    Alternatively, forms can be processed at run time, producing dynamically-
    generated user interfaces. This can be done using the QtUiTools module
    that provides the QUiLoader class to handle forms created with \QD.


    \section2 The UiTools Approach

    A resource file containing a UI file is required to process forms at
    run time. Also, the application needs to be configured to use the QtUiTools
    module. This is done by including the following declarations in a \c CMake
    project file, ensuring that the application is compiled and linked
    appropriately.

    \snippet ../uitools/textfinder/CMakeLists.txt 0
    \snippet ../uitools/textfinder/CMakeLists.txt 1

    For \c qmake:

    \snippet manual/doc_src_designer-manual.pro 0

    The QUiLoader class provides a form loader object to construct the user
    interface. This user interface can be retrieved from any QIODevice, e.g.,
    a QFile object, to obtain a form stored in a project's resource file. The
    QUiLoader::load() function constructs the form widget using the user
    interface description contained in the file.

    The QtUiTools module classes can be included using the following directive:

    \snippet manual/doc_src_designer-manual.cpp 1

    The QUiLoader::load() function is invoked as shown in this code from the
    \l{Text Finder} example:

    \snippet ../uitools/textfinder/textfinder.cpp 4

    In a class that uses QtUiTools to build its user interface at run time, we
    can locate objects in the form using QObject::findChild(). For example, in the
    following code, we locate some components based on their object names and
    widget types:

    \snippet ../uitools/textfinder/textfinder.cpp 1

    Processing forms at run-time gives the developer the freedom to change a
    program's user interface, just by changing the UI file. This is useful
    when customizing programs to suit various user needs, such as extra large
    icons or a different colour scheme for accessibility support.


    \section1 Automatic Connections

    The signals and slots connections defined for compile time or run time
    forms can either be set up manually or automatically, using QMetaObject's
    ability to make connections between signals and suitably-named slots.

    Generally, in a QDialog, if we want to process the information entered by
    the user before accepting it, we need to connect the clicked() signal from
    the \gui OK button to a custom slot in our dialog. We will first show an
    example of the dialog in which the slot is connected by hand then compare
    it with a dialog that uses automatic connection.


    \section2 A Dialog Without Auto-Connect

    We define the dialog in the same way as before, but now include a slot in
    addition to the constructor:

    \snippet noautoconnection/imagedialog.h 0

    The \c checkValues() slot will be used to validate the values provided by
    the user.

    In the dialog's constructor we set up the widgets as before, and connect
    the \gui Cancel button's \l{QPushButton::clicked()}{clicked()} signal to
    the dialog's reject() slot. We also disable the
    \l{QPushButton::autoDefault}{autoDefault} property in both buttons to
    ensure that the dialog does not interfere with the way that the line edit
    handles return key events:

    \snippet noautoconnection/imagedialog.cpp 0
    \dots
    \snippet noautoconnection/imagedialog.cpp 1

    We connect the \gui OK button's \l{QPushButton::clicked()}{clicked()}
    signal to the dialog's checkValues() slot which we implement as follows:

    \snippet noautoconnection/imagedialog.cpp 2

    This custom slot does the minimum necessary to ensure that the data
    entered by the user is valid - it only accepts the input if a name was
    given for the image.

    \section2 Widgets and Dialogs with Auto-Connect

    Although it is easy to implement a custom slot in the dialog and connect
    it in the constructor, we could instead use QMetaObject's auto-connection
    facilities to connect the \gui OK button's clicked() signal to a slot in
    our subclass. \c{uic} automatically generates code in the dialog's
    \c setupUi() function to do this, so we only need to declare and
    implement a slot with a name that follows a standard convention:

    \snippet manual/doc_src_designer-manual.cpp 2

    \note When renaming widgets in the form, the slot names need to be
    adapted accordingly, which can become a maintenance problem.
    For this reason, we recommend against using this in new code.

    Using this convention, we can define and implement a slot that responds to
    mouse clicks on the \gui OK button:

    \snippet autoconnection/imagedialog.h 0

    Another example of automatic signal and slot connection would be the
    \l{Text Finder} with its \c{on_findButton_clicked()}
    slot.

    We use QMetaObject's system to enable signal and slot connections:

    \snippet ../uitools/textfinder/textfinder.cpp 2

    This enables us to implement the slot, as shown below:

    \snippet ../uitools/textfinder/textfinder.cpp 6
    \dots
    \snippet ../uitools/textfinder/textfinder.cpp 8

    Automatic connection of signals and slots provides both a standard naming
    convention and an explicit interface for widget designers to work to. By
    providing source code that implements a given interface, user interface
    designers can check that their designs actually work without having to
    write code themselves.
*/

/*!
    \page designer-using-a-ui-file-python.html
    \previouspage Using a Designer UI File in Your C++ Application
    \nextpage Using Custom Widgets with Qt Widgets Designer

    \title Using a Designer UI File in Your Qt for Python Application

    \section1 Converting the Form to Python Code

    To demonstrate, we use the Qt Widgets animation easing example.

    The application consists of one source file, \c easing.py, a UI
    file \c form.ui, a resource file \c  easing.qrc and the project
    file, \c{easing.pyproject} file in the YAML format:

    \code
    {
        "files": ["easing.qrc", "ui_form.py", "easing.py", "easing_rc.py",
                  "form.ui"]
    }
    \endcode

    The UI file is converted to Python code building the form using the
    \l{User Interface Compiler (uic)}:

    \code
    uic -g python form.ui > ui_form.py
    \endcode

    Since the top level widget is named \c Form, this results in a Python
    class named \c Ui_Form being generated. It provides a function
    \c setupUi(), taking the widget as parameter, which is called to
    create the UI elements:

    \code
    from ui_form import Ui_Form
    ...
    class Window(QtWidgets.QWidget):
        def __init__(self, parent=None):
            super(Window, self).__init__(parent)

            self.m_ui = Ui_Form()
            self.m_ui.setupUi(self)
    \endcode

    Later on, the widgets can be accessed via the \c Ui_Form class:

    \code
    self.m_ui.graphicsView.setScene(self.m_scene)
    \endcode

    Besides \c setupUi(), \c Ui_Form provides another method
    \c retranslateUi(), which can be called in reaction to
    a QEvent of type QEvent.LanguageChange, which indicates
    a change in the application language.

    \section2 The UiTools Approach

    The QUiLoader class provides a form loader object to construct the user
    interface at runtime. This user interface can be retrieved from any
    QIODevice, e.g., a QFile object. The QUiLoader::load() function
    constructs the form widget using the user interface description
    contained in the file.

    It is demonstrated by the uiloader example:

    \code
    from PySide2.QtUiTools import QUiLoader

    if __name__ == '__main__':
        # Some code to obtain the form file name, ui_file_name
        app = QApplication(sys.argv)
        ui_file = QFile(ui_file_name)
        if not ui_file.open(QIODevice.ReadOnly):
            print("Cannot open {}: {}".format(ui_file_name, ui_file.errorString()))
            sys.exit(-1)
        loader = QUiLoader()
        widget = loader.load(ui_file, None)
        ui_file.close()
        if not widget:
            print(loader.errorString())
            sys.exit(-1)
        widget.show()
        sys.exit(app.exec_())
    \endcode

    \section1 Resource imports

    \section2 Single directory usage

    When using icons from \l{The Qt Resource System}{resource files}, say
    \c resources.qrc, \c uic will generate an import of the form:

    \code
    import resources_rc
    \endcode

    This assumes that a file \c resources_rc.py generated by calling the
    \l {Resource Compiler (rcc)} tool (passing the \c {-g python}
    command line option) exists in the same directory as the form source.

    \c uic has a command line option \c --rc-prefix causing the \c rc indicator
    to be prepended:

    \code
    import rc_resources
    \endcode

    The command line option \c --from-imports causes the imports to be generated
    relative to '.':

    \code
    from . import resources_rc
    \endcode

    \section2 Directory trees

    Some projects have more complicated directory trees, for example:

    \badcode
    project
        resources   (resources.qrc)
        ui          (.ui files)
    \endcode

    The resource file is then not in the same directory as the form source
    and the \c .ui files typically have relative paths to the resource files:

    \badcode
    <include location="../resources/resources.qrc"/>
    \endcode

    In this case, the command line option \c --absolute-imports can be used
    to generate an absolute import in Python, resulting in:

    \code
    import resources.resources_rc
    \endcode

    based on the assumption that \c .. is the root directory of the project
    contained in the Python import path list.

    For more deeply nested trees, it is possible to use the
    command line option \c {--python-paths <path list>} to pass a Python
    import path list. \c uic will then try to determine the project root
    by matching the form file path against the path components.

    If \c {--python-paths} is not given, the environment variable
    \c PYTHONPATH is by default checked.
*/

/*!
    \page designer-customizing-forms.html
    \previouspage Using a Designer UI File in Your Qt for Python Application
    \nextpage Using Custom Widgets with Qt Widgets Designer

    \title Customizing Qt Widgets Designer Forms

    \image designer-form-settings.png {Screenshot of form settings window showing
           options to change author, edit layout default and function, include
           hints, and add pixmap function}

    When saving a form in \QD, it is stored as a UI file. Several form
    settings, for example the grid settings or the margin and spacing for the
    default layout, are stored along with the form's components. These settings
    are used when the \l uic generates the form's C++ code. For more
    information on how to use forms in your application, see the
    \l{Using a Designer UI File in Your C++ Application} section.


    \section1 Modifying the Form Settings

    To modify the form settings, open the \gui Form menu and select \gui{Form
    Settings...}

    In the forms settings dialog you can specify the \gui Author of the form.

    You can also alter the margin and spacing properties for the form's default
    layout (\gui {Layout Default}). These default layout properties will be
    replaced by the corresponding \gui {Layout Function}, if the function is
    specified, when \c uic generates code for the form. The form settings
    dialog lets you specify functions for both the margin and the spacing.

    \target LayoutFunction
    \table
    \row
    \li \inlineimage designer-form-layoutfunction.png {Screenshot showing the
                     option to enable or disable layout function and to edit
                     margin and spacing of layout function}
    \li \b{Layout Function}

    The default layout properties will be replaced by the corresponding
    \gui{Layout Function}, when \c uic generates code for the form. This is
    useful when different environments requires different layouts for the same
    form.

    To specify layout functions for the form's margin and spacing, check the
    \gui{Layout Function} group box to enable the line edits.
    \endtable

    You can also specify the form's \gui{Include Hints}; i.e., provide a list
    of the header files which will then be included in the form window's
    associated UI file. Header files may be local, i.e., relative to the
    project's directory, \c "mywidget.h", or global, i.e. part of Qt or the
    compilers standard libraries: \c <QtWidgets/QWidget>.

    Finally, you can specify the function used to load pixmaps into the form
    window (the \gui {Pixmap Function}).
*/


/*!
    \page designer-using-custom-widgets.html
    \previouspage Customizing Qt Widgets Designer Forms
    \nextpage Creating Custom Widgets for Qt Widgets Designer

    \title Using Custom Widgets with Qt Widgets Designer

    \QD can display custom widgets through its extensible plugin mechanism,
    allowing the range of designable widgets to be extended by the user and
    third parties. Alternatively, it is possible
    to use existing widgets as placeholders for widget classes that provide
    similar APIs.


    \section1 Handling Custom Widgets

    Although \QD supports all of the standard Qt widgets, some specialized
    widgets may not be available as standard for a number of reasons:

    \list
        \li Custom widgets may not be available at the time the user interface
           is being designed.
        \li Custom widgets may be platform-specific, and designers may be
           developing the user interface on a different platform to end users.
        \li The source code for a custom widget is not available, or the user
           interface designers are unable to use the widget for non-technical
           reasons.
    \endlist

    In the above situations, it is still possible to design forms with the aim
    of using custom widgets in the application. To achieve this, we can use
    the widget promotion feature of \QD.

    In all other cases, where the source code to the custom widgets is
    available, we can adapt the custom widget for use with \QD.


    \section2 Promoting Widgets

    \image designer-promoting-widgets.png {Screenshot of the Promoted Widgets window
           showing options to add a custom widget class by specifying a base class,
           promoted class name, and header file}

    If some forms must be designed, but certain custom widgets are unavailble
    to the designer, we can substitute similar widgets to represent the missing
    widgets. For example, we might represent instances of a custom push button
    class, \c MyPushButton, with instances of QPushButton and promote these to
    \c MyPushButton so that \l{uic.html}{uic} generates suitable code for this
    missing class.

    When choosing a widget to use as a placeholder, it is useful to compare the
    API of the missing widget with those of standard Qt widgets. For
    specialized widgets that subclass standard classes, the obvious choice of
    placeholder is the base class of the custom widget; for example, QSlider
    might be used for specialized QSlider subclasses.

    For specialized widgets that do not share a common API with standard Qt
    widgets, it is worth considering adapting a custom widget for use in \QD.
    If this is not possible then QWidget is the obvious choice for a
    placeholder widget since it is the lowest common denominator for all
    widgets.

    To add a placeholder, select an object of a suitable base class and choose
    \gui{Promote to ...} from the form's context menu. After entering the class
    name and header file in the lower part of the dialog, choose \gui{Add}. The
    placeholder class will now appear along with the base class in the upper
    list. Click the \gui{Promote} button to accept this choice.

    Now, when the form's context menu is opened over objects of the base class,
    the placeholder class will appear in the \gui{Promote to} submenu, allowing
    for convenient promotion of objects to that class.

    A promoted widget can be reverted to its base class by choosing
    \gui{Demote to} from the form's context menu.


    \section2 User Defined Custom Widgets

    Custom widgets can be adapted for use with \QD, giving designers the
    opportunity to configure the user interface using the actual widgets that
    will be used in an application rather than placeholder widgets. The process
    of creating a custom widget plugin is described in the
    \l{Creating Custom Widgets for Qt Widgets Designer} chapter of this manual.

    To use a plugin created in this way, it is necessary to ensure that the
    plugin is located on a path that \QD searches for plugins. Generally,
    plugins stored in \c{$QTDIR/plugins/designer} will be loaded when \QD
    starts. Further information on building and installing plugins can be found
    \l{Creating Custom Widgets for Qt Widgets Designer#BuildingandInstallingthePlugin}
    {here}. You can also refer to the \l{How to Create Qt Plugins}
    {Plugins HOWTO} document for information about creating plugins.
*/


/*!
    \page designer-creating-custom-widgets.html
    \previouspage Using Custom Widgets with Qt Widgets Designer
    \nextpage Creating Custom Widget Extensions

    \title Creating Custom Widgets for Qt Widgets Designer

    \QD's plugin-based architecture allows user-defined and third party custom
    widgets to be edited just like you do with standard Qt widgets. All of the
    custom widget's features are made available to \QD, including widget
    properties, signals, and slots. Since \QD uses real widgets during the form
    design process, custom widgets will appear the same as they do when
    previewed.

    The \l QtDesigner module provides you with the ability to create custom
    widgets in \QD.


    \section1 Getting Started

    To integrate a custom widget with \QD, you require a suitable description
    for the widget and an appropriate project file.


    \section2 Providing an Interface Description

    To inform \QD about the type of widget you want to provide, create a
    subclass of QDesignerCustomWidgetInterface that describes the various
    properties your widget exposes. Most of these are supplied by functions
    that are pure virtual in the base class, because only the author of the
    plugin can provide this information.

    \table
        \header
            \li  Function
            \li  Description of the return value
        \row
            \li  \c name()
            \li  The name of the class that provides the widget.
        \row
            \li  \c group()
            \li  The group in \QD's widget box that the widget belongs to.
        \row
            \li  \c toolTip()
            \li  A short description to help users identify the widget in \QD.
        \row
            \li  \c whatsThis()
            \li  A longer description of the widget for users of \QD.
        \row
            \li  \c includeFile()
            \li  The header file that must be included in applications that use
                this widget. This information is stored in UI files and will
                be used by \c uic to create a suitable \c{#includes} statement
                in the code it generates for the form containing the custom
                widget.
        \row
            \li  \c icon()
            \li  An icon that can be used to represent the widget in \QD's
                widget box.
        \row
            \li  \c isContainer()
            \li  True if the widget will be used to hold child widgets;
                false otherwise.
        \row
            \li  \c createWidget()
            \li  A QWidget pointer to an instance of the custom widget,
                constructed with the parent supplied.
                \note createWidget() is a factory function responsible for
                creating the widget only. The custom widget's properties will
                not be available until load() returns.
        \row
            \li  \c domXml()
            \li  A description of the widget's properties, such as its object
                name, size hint, and other standard QWidget properties.
        \row
            \li  \c codeTemplate()
            \li  This function is reserved for future use by \QD.
    \endtable

    Two other virtual functions can also be reimplemented:

    \table
        \row
            \li  \c initialize()
            \li  Sets up extensions and other features for custom widgets. Custom
                container extensions (see QDesignerContainerExtension) and task
                menu extensions (see QDesignerTaskMenuExtension) should be set
                up in this function.
        \row
            \li  \c isInitialized()
            \li  Returns true if the widget has been initialized; returns false
                otherwise. Reimplementations usually check whether the
                \c initialize() function has been called and return the result
                of this test.
    \endtable


    \section2 Notes on the \c{domXml()} Function

    The \c{domXml()} function returns a UI file snippet that is used by
    \QD's widget factory to create a custom widget and its applicable
    properties.

    Since Qt 4.4, \QD's widget box allows for a complete UI file to
    describe \b one custom widget. The UI file can be loaded using the
    \c{<ui>} tag. Specifying the <ui> tag allows for adding the <customwidget>
    element that contains additional information for custom widgets. The
    \c{<widget>} tag is sufficient if no additional information is required

    If the custom widget does not provide a reasonable size hint, it is
    necessary to specify a default geometry in the string returned by the
    \c domXml() function in your subclass. For example, the
    \c AnalogClockPlugin provided by the \l{customwidgetplugin}
    {Custom Widget Plugin} example, defines a default widgetgeometry in the
    following way:

    \dots
    \snippet customwidgetplugin/customwidgetplugin.cpp 11
    \dots

    An additional feature of the \c domXml() function is that, if it returns
    an empty string, the widget will not be installed in \QD's widget box.
    However, it can still be used by other widgets in the form. This feature
    is used to hide widgets that should not be explicitly created by the user,
    but are required by other widgets.

    A complete custom widget specification looks like:

    \code
<ui language="c++"> displayname="MyWidget">
    <widget class="widgets::MyWidget" name="mywidget"/>
    <customwidgets>
        <customwidget>
            <class>widgets::MyWidget</class>
            <addpagemethod>addPage</addpagemethod>
            <propertyspecifications>
                <stringpropertyspecification name="fileName" notr="true" type="singleline"/>
                <stringpropertyspecification name="text" type="richtext"/>
                <tooltip name="text">Explanatory text to be shown in Property Editor</tooltip>
            </propertyspecifications>
        </customwidget>
    </customwidgets>
</ui>
    \endcode

    Attributes of the \c{<ui>} tag:
        \table
        \header
            \li  Attribute
            \li  Presence
            \li  Values
            \li  Comment
        \row
            \li  \c{language}
            \li  optional
            \li  "c++", "jambi"
            \li  This attribute specifies the language the custom widget is intended for.
                It is mainly there to prevent C++-plugins from appearing in Qt Jambi.
        \row
            \li \c{displayname}
            \li optional
            \li Class name
            \li The value of the attribute appears in the Widget box and can be used to
                strip away namespaces.
    \endtable

    The \c{<addpagemethod>} tag tells \QD and \l uic which method should be used to
    add pages to a container widget. This applies to container widgets that require
    calling a particular method to add a child rather than adding the child by passing
    the parent. In particular, this is relevant for containers that are not a
    a subclass of the containers provided in \QD, but are based on the notion
    of \e{Current Page}. In addition,  you need to provide a container extension
    for them.

    The \c{<propertyspecifications>} element can contain a list of property meta information.

    The tag \c{<tooltip>} may be used to specify a tool tip to be shown in Property Editor
    when hovering over the property. The property name is given in the attribute \c name and
    the element text is the tooltip. This functionality was added in Qt 5.6.

    For properties of type string, the \c{<stringpropertyspecification>} tag can be used.
    This tag has the following attributes:

    \table
        \header
            \li  Attribute
            \li  Presence
            \li  Values
            \li  Comment
        \row
            \li  \c{name}
            \li  required
            \li  Name of the property
        \row
            \li \c{type}
            \li required
            \li See below table
            \li The value of the attribute determines how the property editor will handle them.
        \row
            \li \c{notr}
            \li optional
            \li "true", "false"
            \li If the attribute is "true", the value is not meant to be translated.
    \endtable

    Values of the \c{type} attribute of the string property:

    \table
        \header
            \li  Value
            \li  Type
        \row
            \li \c{"richtext"}
            \li Rich text.
        \row
            \li \c{"multiline"}
            \li Multi-line plain text.
        \row
            \li \c{"singleline"}
            \li Single-line plain text.
        \row
            \li \c{"stylesheet"}
            \li A CSS-style sheet.
        \row
            \li \c{"objectname"}
            \li An object name (restricted set of valid characters).
        \row
            \li \c{"url"}
            \li URL, file name.
    \endtable

    \section1 Plugin Requirements

    In order for plugins to work correctly on all platforms, you need to ensure
    that they export the symbols needed by \QD.

    First of all, the plugin class must be exported in order for the plugin to
    be loaded by \QD. Use the Q_PLUGIN_METADATA() macro to do this. Also, the
    QDESIGNER_WIDGET_EXPORT macro must be used to define each custom widget class
    within a plugin, that \QD will instantiate.


    \section1 Creating Well Behaved Widgets

    Some custom widgets have special user interface features that may make them
    behave differently to many of the standard widgets found in \QD.
    Specifically, if a custom widget grabs the keyboard as a result of a call
    to QWidget::grabKeyboard(), the operation of \QD will be affected.

    To give custom widgets special behavior in \QD, provide an implementation
    of the initialize() function to configure the widget construction process
    for \QD specific behavior. This function will be called for the first time
    before any calls to createWidget() and could perhaps set an internal flag
    that can be tested later when \QD calls the plugin's createWidget()
    function.


    \target BuildingandInstallingthePlugin
    \section1 Building and Installing the Plugin

    \section2 A Simple Plugin

    The \l{Custom Widget Plugin} demonstrates a simple \QD plugin.

    The project file for a plugin must specify the headers and sources for
    both the custom widget and the plugin interface. Typically, this file only
    has to specify that the plugin's project will be built as a library, but
    with specific plugin support for \QD. For \c CMake, this is done with
    the following declarations:

    \snippet customwidgetplugin/CMakeLists.txt 0
    \snippet customwidgetplugin/CMakeLists.txt 1
    \snippet customwidgetplugin/CMakeLists.txt 2

    The link libraries list specifies \c Qt::UiPlugin. This indicates that
    the plugin uses the abstract interfaces QDesignerCustomWidgetInterface
    and QDesignerCustomWidgetCollectionInterface only and has no linkage
    to the \QD libraries. When accessing other interfaces of \QD that have
    linkage, \c Designer should be used instead; this ensures that the plugin
    dynamically links to the \QD libraries and has a run-time dependency on
    them.

    It is also necessary to ensure that the plugin is installed together with
    other \QD widget plugins:

    \snippet customwidgetplugin/CMakeLists.txt 3
    \snippet customwidgetplugin/CMakeLists.txt 4

    For \c qmake:

    \snippet customwidgetplugin/customwidgetplugin.pro 0
    \snippet customwidgetplugin/customwidgetplugin.pro 2

    The \c QT variable contains the keyword \c uiplugin, which is
    the equivalent of the \c Qt::UiPlugin library.

    It is also necessary to ensure that the plugin is installed together with
    other \QD widget plugins:

    \snippet manual/doc_src_designer-manual.pro 4

    The \c $[QT_INSTALL_PLUGINS] variable is a placeholder to the location of
    the installed Qt plugins. You can configure \QD to look for plugins in
    other locations by setting the \c QT_PLUGIN_PATH environment variable
    before running the application.

    \note \QD will look for a \c designer subdirectory in each path supplied.

    See QCoreApplication::libraryPaths() for more information about customizing
    paths for libraries and plugins with Qt applications.

    If plugins are built in a mode that is incompatible with \QD, they will
    not be loaded and installed. For more information about plugins, see the
    \l{plugins-howto.html}{Plugins HOWTO} document.

    \section2 Splitting up the Plugin

    The simple approach explained above introduces a problem particularly
    when using the other interfaces of \QD that have linkage:
    The application using the custom widget will then depend on
    \QD headers and libraries. In a real world scenario, this is not desired.

    The following sections describe how to resolve this.

    \section3 Linking the Widget into the Application

     When using \c qmake, the source and header file of the custom widget
     can be shared between the application and \QD by creating a \c{.pri}
     file for inclusion:

     \code
     INCLUDEPATH += $$PWD
     HEADERS += $$PWD/analogclock.h
     SOURCES += $$PWD/analogclock.cpp
     \endcode

     This file would then be included by the \c{.pro} file of the plugin and
     the application:

     \code
     include(customwidget.pri)
     \endcode

    When using \c CMake, the source files of the widget can similarly be
    added to the application project.

    \section3 Sharing the Widget Using a Library

    Another approach is to put the widget into a library that is linked to
    the \QD plugin as well as to the application. It is recommended to
    use static libraries to avoid problems locating the library at run-time.

    For shared libraries, see \l{sharedlibrary.html}{Creating Shared Libraries}.

    \section3 Using the Plugin with QUiLoader

    The preferred way of adding custom widgets to QUiLoader is to subclass it
    reimplementing QUiLoader::createWidget().

    However, it is also possible to use \QD custom widget plugins
    (see QUiLoader::pluginPaths() and related functions). To avoid having
    to deploy the \QD libraries onto the target device, those plugins should
    have no linkage to the \QD libraries (\c {QT = uiplugin}, see
    \l{Creating Custom Widgets for Qt Widgets Designer#BuildingandInstallingthePlugin}).

    \section1 Related Examples

    For more information on using custom widgets in \QD, refer to the
    \l{customwidgetplugin}{Custom Widget Plugin} and
    \l{taskmenuextension}{Task Menu Extension} examples for more
    information about using custom widgets in \QD. Also, you can use the
    QDesignerCustomWidgetCollectionInterface class to combine several custom
    widgets into a single library.
*/


/*!
    \page designer-creating-custom-widgets-extensions.html
    \previouspage Creating Custom Widgets for Qt Widgets Designer
    \nextpage Qt Widgets Designer's UI File Format

    \title Creating Custom Widget Extensions

    Once you have a custom widget plugin for \QD, you can provide it with the
    expected behavior and functionality within \QD's workspace, using custom
    widget extensions.


    \section1 Extension Types

    There are several available types of extensions in \QD. You can use all of
    these extensions in the same pattern, only replacing the respective
    extension base class.

    QDesignerContainerExtension is necessary when implementing a custom
    multi-page container.

    \table
        \row
            \li  \inlineimage designer-manual-taskmenuextension.png {Screenshot
                              of designer editor canvas showing a simple custom
                              widget with a context menu open, highlighting the
                              “Edit State" option}
            \li  \b{QDesignerTaskMenuExtension}

        QDesignerTaskMenuExtension is useful for custom widgets. It provides an
        extension that allows you to add custom menu entries to \QD's task
        menu.

        The \l{taskmenuextension}{Task Menu Extension} example
        illustrates how to use this class.

        \row
            \li  \inlineimage designer-manual-containerextension.png {Screenshot
                              of designer editor showing a container and an open
                              context menu}
            \li  \b{QDesignerContainerExtension}

        QDesignerContainerExtension is necessary when implementing a custom
        multi-page container. It provides an extension that allows you to add
        and delete pages for a multi-page container plugin in \QD.

        The \l{containerextension}{Container Extension} example
        further explains how to use this class.

        \note It is not possible to add custom per-page properties for some
        widgets (e.g., QTabWidget) due to the way they are implemented.
    \endtable

    \table
        \row
            \li  \inlineimage designer-manual-membersheetextension.png {Screenshot
                              of "Configure Connecttion" showing which functions
                              should the connected widgets send to each other}
            \li  \b{QDesignerMemberSheetExtension}

        The QDesignerMemberSheetExtension class allows you to manipulate a
        widget's member functions displayed when connecting signals and slots.

        \row
            \li  \inlineimage designer-manual-propertysheetextension.png {Screenshot
                              of "Property Editor" showing the properties, and
                              settings used for an object}
            \li  \b{QDesignerPropertySheetExtension,
                QDesignerDynamicPropertySheetExtension}

        These extension classes allow you to control how a widget's properties
        are displayed in \QD's property editor.
    \endtable

\omit
     \row
        \li
        \li \b {QDesignerScriptExtension}

         The QDesignerScriptExtension class allows you to define script
         snippets that are executed when a form is loaded. The extension
         is primarily intended to be used to set up the internal states
         of custom widgets.
    \endtable
\endomit


    \QD uses the QDesignerPropertySheetExtension and the
    QDesignerMemberSheetExtension classes to feed its property and signal and
    slot editors. Whenever a widget is selected in its workspace, \QD will
    query for the widget's property sheet extension; likewise, whenever a
    connection between two widgets is requested, \QD will query for the
    widgets' member sheet extensions.

    \warning All widgets have default property and member sheets. If you
    implement custom property sheet or member sheet extensions, your custom
    extensions will override the default sheets.


    \section1 Creating an Extension

    To create an extension you must inherit both QObject and the appropriate
    base class, and reimplement its functions. Since we are implementing an
    interface, we must ensure that it is made known to the meta object system
    using the Q_INTERFACES() macro in the extension class's definition. For
    example:

    \snippet manual/doc_src_designer-manual.cpp 7

    This enables \QD to use the qobject_cast() function to query for supported
    interfaces using a QObject pointer only.


    \section1 Exposing an Extension to Qt Widgets Designer

    In \QD the extensions are not created until they are required. For this
    reason, when implementing extensions, you must subclass QExtensionFactory
    to create a class that is able to make instances of your extensions. Also,
    you must register your factory with \QD's extension manager; the extension
    manager handles the construction of extensions.

    When an extension is requested, \QD's extension manager will run through
    its registered factories calling QExtensionFactory::createExtension() for
    each of them until it finds one that is able to create the requested
    extension for the selected widget. This factory will then make an instance
    of the extension.

    \image qtdesignerextensions.png {Diagram showing relation between
           \QD components}


    \section2 Creating an Extension Factory

    The QExtensionFactory class provides a standard extension factory, but it
    can also be used as an interface for custom extension factories.

    The purpose is to reimplement the QExtensionFactory::createExtension()
    function, making it able to create your extension, such as a
     \l{containerextension}{MultiPageWidget} container extension.

    You can either create a new QExtensionFactory and reimplement the
    QExtensionFactory::createExtension() function:

    \snippet manual/doc_src_designer-manual.cpp 8

    or you can use an existing factory, expanding the
    QExtensionFactory::createExtension() function to enable the factory to
    create your custom extension as well:

    \snippet manual/doc_src_designer-manual.cpp 9


    \section2 Accessing Qt Widgets Designer's Extension Manager

    When implementing a custom widget plugin, you must subclass the
    QDesignerCustomWidgetInterface to expose your plugin to \QD. This is
    covered in more detail in the
    \l{Creating Custom Widgets for Qt Widgets Designer} section. The registration of
    an extension factory is typically made in the
    QDesignerCustomWidgetInterface::initialize() function:

    \snippet manual/doc_src_designer-manual.cpp 10

    The \c formEditor parameter in the
    QDesignerCustomWidgetInterface::initialize() function is a pointer to \QD's
    current QDesignerFormEditorInterface object. You must use the
    QDesignerFormEditorInterface::extensionManager() function to retrieve an
    interface to \QD's extension manager. Then you use the
    QExtensionManager::registerExtensions() function to register your custom
    extension factory.


    \section1 Related Examples

    For more information on creating custom widget extensions in \QD, refer to
    the \l{taskmenuextension}{Task Menu Extension} and
    \l{containerextension}{Container Extension} examples.
*/


/*!
    \page designer-ui-file-format.html
    \previouspage Creating Custom Widget Extensions

    \title Qt Widgets Designer's UI File Format

    The \c UI file format used by \QD is described by the
    \l{http://www.w3.org/XML/Schema}{XML schema} presented below,
    which we include for your convenience. Be aware that the format
    may change in future Qt releases.

    \quotefile ../../../../data/ui4.xsd
*/
