Fix shift-action modifier in context menu on the desktop
This is a fix for bug 425997. The new attempt is to install an event filter on QApplication as long as the context menu is open.
There is a very similar fix for Dolphin, because Dolphin had the exact same problem.
Commit message:
Before this patch, the shift-action modifier in context menus did not
work when a sub-context menu is open, that does not have the main
context menu as its parent.
The new fix installs an event filter on QApplication whenever a new
context menu is opened to make the context menu aware of shift-presses
even when a sub-context menu is in focus.
BUG: 425997
FIXED-IN: 5.22