The completer popup has focus, making QShortcut direct to it's window
rather than to the window the completer belongs to. As QShortcut handles
the case for Tool windows that have a parent, but doens't do the same
for popups. And they shouldn't be treated the same way, as a context
menu popup for a e.g. text edit should in fact block the text edit's
shortcuts while open.
However, the completer popup is special, in that it explicitly makes the
widget completes for its focusProxy, which is what we can use to fix
this issue.
Change-Id: Ie7177d39668b3af14a1d9e0ee5d93eca9c67c8af
Fixes: QTBUG-4485
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>