If QDockWidgets are "shown" in QWidget sense a second time, no resize or
move events might happen as the widget has already been layouted before
and might simply reappear at same position with same size.
The old logic did not catch this, so would keep an outdated state stored
in the auto-save settings of the window, which then would result in wrong
state being enforced on restoring.

Open KDevelop, open a toolview which was not open before (e.g. "Search in
all Files"), switch to another toolview not open before, then switch back
to the first toolview. Now either switch the currently viewed document
(e.g. open another file) or quit & reopen KDevelop.
Before the first toolview would hide itself despite officially being still
visible, with this patch the state is properly hold (when internally being
restored, like during finalizeGUI on KXmlGui client change).