How to maximize QDialog to full screen? - qt

Question

I have an application in full screen mode when taskbar (placed on bottom of screen) is invisible. In this application it is possible to display a dialog, but if I maximize it (using maximize button or programmatically), the dialog will not appear to full screen. It just appears like the taskbar was there.
So is it possible to maximize dialog to full screen? But it is necessary to keep its titlebar with buttons for minimizing, maximizing and closing.
Edit:
I didn`t add any code, because I found nothing useful. But ok, here is code which does not work:
// main.cpp
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.showFullScreen();
return a.exec();
}
// mainwindow.cpp
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
{
QDialog *dialog = new QDialog(this);
// only for better visibility of the dialog
dialog->setStyleSheet("background: green");
// This does not work because the dialog is displayed without a titlebar
// and buttons for minimizing, maximizing and closing.
// dialog->setWindowState(Qt::WindowFullScreen);
// dialog->show();
// or (it is the same)
// dialog->showFullScreen();
// This does not display the dialog on the full screen.
dialog->showMaximized();
}
// mainwindow.h
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = 0);
~MainWindow() {}
};

Answer 1

It depends on how your taskbar settings are set.
fi. on windows10:
if I use "Automaticaly hide the taskbar in desktop mode" ON
then Maximizing will take only the part of the screen above the taskbar.
If the above setting is off
then Maximizing will take the whole screen.
You can use QScreen to query the available space and steer the maximum size in code also:
Qt Docs QScreen