shell-global.[ch]: Add shell_global_display_is_grabbed() that
uses the newly added meta_display_get_grab_op() to check
for existing grabs.
shell-status-menu.[ch]: Add shell_status_menu_is_active() to
check if the menu is popped up. Check for active grabs before
popping the menu up. Use gtk_menu_popdown() rather than
gtk_widget_hide(). Remove an excess gtk_widget_show() and
some excess casts.
panel.js: Check whether the status menu is popped up after button
release, and if it's not popped up, unhighlight the button.
Reported by Nuno Donato
http://bugzilla.gnome.org/show_bug.cgi?id=593362
1340413740