Toplevel Widgets

This example demonstrates the use of Qt's widget flags to provide toplevel widgets with customized window decorations.

It provides a graphical user interface for selecting different options for widget decoration and behavior, and passes the appropriate widget flags to the QWidget constructor. QWidget::reparent() is used to change the widget flags at runtime.

Warning: Note that the interpretation and functionality of the widget flags depends on the window manager used when running the application. Many window managers do not support every possible flag combination.

The user interface providing the different options was created using Qt Designer. The different options are explained in the user interface through the use of tooltips and What's This help. Load the options.ui file into Qt Designer for more details.

    #include <qapplication.h>
    #include "options.h"

    int main( int argc, char ** argv )
    {
        QApplication a( argc, argv );
        OptionsDialog dlg;
        return dlg.exec();
    }

The main function creates and displays the dialog for the user interface. Note that this dialog is modal.

The code relevant for this example is in the options.ui.h file.

    void OptionsDialog::apply()
    {
        WFlags f = WDestructiveClose | WType_TopLevel | WStyle_Customize;

The apply() slot declares the widget flag variable f and initializes it with the values

• WDestructiveClose - the widget will be automatically destroyed when it is closed,
• WType_TopLevel - the widget will be top level even if it has a parent widget, and
• WStyle_Customize - the flags override the default values

        if ( bgBorder->isChecked() ) {
            if ( rbBorderNormal->isChecked() )
                f |= WStyle_NormalBorder;
            else if ( rbBorderDialog->isChecked() )
                f |= WStyle_DialogBorder;

            if ( bgTitle->isChecked() ) {
                f |= WStyle_Title;
                if ( cbTitleSystem->isChecked() )
                    f |= WStyle_SysMenu;
                if ( cbTitleMinimize->isChecked() )
                    f |= WStyle_Minimize;
                if ( cbTitleMaximize->isChecked() )
                    f |= WStyle_Maximize;
                if ( cbTitleContext->isChecked() )
                    f |= WStyle_ContextHelp;
            }

        } else {
            f |= WStyle_NoBorder;
        }

        QWidget *parent = this;
        if ( cbBehaviorTaskbar->isChecked() ) {
            parent = 0;
            f |= WGroupLeader;
        }

To provide a taskbar entry the widget must have no parent, in which case we need to use the WGroupLeader flag to prevent blocking through the modal main dialog. Applications that can have multiple toplevel windows open simultaneously should use this combination.

        if ( cbBehaviorStays->isChecked() )
            f |= WStyle_StaysOnTop /*| WX11BypassWM*/;

        if ( cbBehaviorPopup->isChecked() )
            f |= WType_Popup;

        if ( cbBehaviorModal->isChecked() )
            f |= WShowModal;

        if ( cbBehaviorTool->isChecked() )
            f |= WStyle_Tool;

        if ( !widget ) {
            widget = new QVBox( parent, 0, f );
            widget->setMargin( 20 );
            QPushButton *okButton = new QPushButton( "Close", widget );
            connect( okButton, SIGNAL(clicked()), widget, SLOT(close()) );
            widget->move( pos() );
            widget->show();

        } else {
            widget->reparent( parent, f, widget->geometry().topLeft(), TRUE );
        }

        widget->setCaption( leCaption->text() );
        widget->setIcon( leIcon->text() );
    }