Center dialog on screen problems

[lalesculiviu]

Hello. I am using this code to center a dialog on the screen:

void centerWidgetOnScreen(QWidget* widget)
{
	QRect rect = QApplication::desktop()->availableGeometry(widget);
 
	widget->move(rect.center() - widget->rect().center());
}

void centerWidgetOnScreen(QWidget* widget)
{
	QRect rect = QApplication::desktop()->availableGeometry(widget);
	 
	widget->move(rect.center() - widget->rect().center());
}

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(where widget is in fact a QDialog*).

But the dialog appears a bit to the right (maybe 10 pixels) and too low (maybe 30 pixels, considering also the task bar).

What am I doing wrong?

I also tried this:

QRect frect=widget->frameGeometry();
frect.moveCenter(QApplication::desktop()->availableGeometry(widget).center());
//frect.moveCenter(QDesktopWidget().availableGeometry(widget).center());
widget->move(frect.topLeft());

QRect frect=widget->frameGeometry();
frect.moveCenter(QApplication::desktop()->availableGeometry(widget).center());
//frect.moveCenter(QDesktopWidget().availableGeometry(widget).center());
widget->move(frect.topLeft());

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But does not work under Linux. By the way, which should I use, QApplication::desktop() or QDesktopWidget()?