With nullptr a parent is searched for and assigned (unless NoParent is
set which means no parent)
since...
commit dd46727b99
Author: Caolán McNamara <caolanm@redhat.com>
Date: Tue Apr 5 15:27:38 2016 +0100
Resolves; tdf#87120 no keyboard navigation inside floating windows
lets try and treat these the same as we do normal toplevels
like dialogs if they popup with GrabFocus.
This way focus can be set on widgets inside the floating windows, and
so keyboard traversal of widgets etc all works.
I believe an active menu is allowed as a parent (which I'll investigate and see
if we can fix or revert that if necessary), but its good practice to explicitly
set the right parent rather than depending on what happens to be on top anyway.
Change-Id: I744f6d9bc133058a4a9db94d6c27d2e36e22179e
a7a96078ff