Double click on DockWidget close button will float the widget.

Repro in designer:
1) Create new Main Window.
2) Add multiple Dock Widgets to left side.
3) Preview the window.
4) Rapidly click the top Dock Widget's close button.

This will close one widget after another, but after the first click the second widget receives a double click event (I suspect) and floats instead of closing. In my main app this seems to float the Dock Widget contents, while closing the Dock Widget itself, resulting in a floating widget with no title bar, or close/float buttons.