Fixed|Task Bar: Close the DE menu if the task bar is closed

The task bar is never hidden so its children keep getting events even
though it's closed.

doomsday/client/src/ui/widgets/taskbarwidget.cpp

@@ -392,6 +392,7 @@ void TaskBarWidget::close()
         d->status->setOpacity(0, .2f);
 
         d->console->closeLog();
+        d->mainMenu->close();
 
         // Clear focus now; callbacks/signal handlers may set the focus elsewhere.
         if(hasRoot()) root().setFocus(0);