When I launch winswitch, I am unable to bring the window / application into focus on Gnome3. Installing the extension topicons solved the problem as the FAQ said, but it took a long time to figure out that this was the issue and remedy. Starting in window mode instead of tray could help this? Sure, it's the Gnome teams fault but it's still sadly winswitch that will not be used.
Love your application :-)
This is xpra's bug tracker, please file winswitch-only bugs here
As for your question... I don't think there is a sane way of detecting when gnome3 is in broken mode (since it is broken by default, and the presence of the specific extensions that restore functionality is not exposed).
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/432