It should not be possible to close a non-closable floating QDockWidget with keyboard shortcuts

Hi all

This surfaced in KDE Bug #488597. I later on reported this problem as KDE Bug #488616 (as I thought this would be a window manager issue), but there I was told this was an upstream issue and thus I should report it to Qt directly.

The problem is that a QDockWidget that is declared as non-closable but as floatable cannot be closed by clicking an "X" button (it's omitted then), but one can actually close such a floating dock nevertheless by using a keyboard shortcut (Alt+F4).

After that, there's no way to re-show that closed dock, as the menu bar's context menu containing checkboxes for all dock widgets is grayed out (it becomes enabled when adding docks with the QDockWidget::DockWidgetClosable feature set). The only way to get the dock back is to delete the window state from the rc file (in case of KGeoTag, as the default dock arrangement will be restored then).

My understanding is that a QDockWidget that is marked as not closable should not only not be closable by omitting the "X"/"Close" button, but also an attempt to close it using keyboard shortcuts should be ignored, to also prevent it from closing this way.

Cheers, Tobias