which is an issue since...

commit dd46727b
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.

which allows keyboard focus inside floating windows to allow a11y keyboard
navigation inside them without jumping through difficult hoops.

Change-Id: I6024c048e80d09a70cb3a628378975248a55d6b6