Using a QDockwidget when it is undocked will not get focus correctly when you click on it, so somethimes you need to give it focus by clicking on window title.

Use the attached example to reproduce this issue.

In the example, undock one of the DowckWidgets. Then click in the central widget so that it has focus. Then click on the label in the undocked widget. You can see that the central widget still has the focus. This is different from the behavoiur on Windows and Mac Cocoa builds where the focus is set to the undocked widget.