QDockWidget default title not respecting setContentsMargins

[Erika]

I've discovered that if you call setContentsMargins on a dock widget, the default title bar remains left aligned and at the fixed width, leaving unusually awkward spacing to the left. If the dockwidget is floating, this is a non-issue, with margins added as expected, however I'm not sure of the best way to resolve this when docked.

Simple example:

#include <QtWidgets\QApplication>
#include <QtWidgets\QMainWindow>
#include <QtWidgets\QDockWidget>
int main(int argc, char *argv[])
{ 	QApplication app(argc, argv);
	app.setApplicationName("Dock Margins Example");
	QMainWindow mainWin;

	// setup widgets
	QDockWidget exampleDock(&mainWin);
	QWidget dockContents;

	dockContents.setStyleSheet(QStringLiteral("background: #FFFFFF;")); // contents colouring
	exampleDock.setWidget(&dockContents);
	mainWin.addDockWidget(Qt::LeftDockWidgetArea, &exampleDock);
	exampleDock.setWindowTitle("Example Dock");
	exampleDock.setContentsMargins(30, 30, 30, 30);
	
	mainWin.show();
	return app.exec();
}

Docked Issues:

Floating OK:

I've also noticed that the top margin appears ignored while docked (seems set as the same as title's height), but as-expected when floating.

Any suggestions on how to resolve the offset title (without having to create a custom title widget), or is it a bug? I've tried a few style changes, but nothing successful so far.

[Chris Kawa]

Looks like a bug. You should report it. The content margins feature has quite a few glitches. I've seen similar problems in other circumstances. It's not a very often used feature so these problems probably get overlooked.

As a workaround you can place a dummy widget and the real content inside it. You can then set the margins on the dummy or on its layout.

[kshegunov]

@Erika
Instead of this:

exampleDock.setContentsMargins(30, 30, 30, 30);

You could try something along the lines of:

exampleDock.layout()->setContentsMargins(30, 30, 30, 30);

Although, I'm not quite sure it'll work.

Kind regards.

[Erika]

@kshegunov Thanks. Unfortunately that doesn't have any impact.

[Erika]

@Chris-Kawa Thanks. I agree it seems like a bug, and have now reported it: https://bugreports.qt.io/browse/QTBUG-51359. I figure the widget-inside-widget would be a workable alternative, but was hoping to avoid that route. C'est la vie.