GlobalActions: Fix dialog dismissal

The themeability of the global actions dialog introduced by
change I644e2e8d7d4abf07bae639b606197d691f16adac broke the
hook that prevented multiple instances of that dialog, and
multiple instances of it will cause framework crashes due to
mismatches variable references (besides looking weird).

Fix it by restoring the original dismissal condition and forcing
a recreation of the theme context if necessary.

Change-Id: Ic6e06bef18fa9e09c84c774fa273f1b7e3bf9630