I guess I just figured it out!
Both Ring and Shift Switcher, in Ubuntu, use Super+Tab by default instead of Alt+Tab so they don't conflict with Untity's Switcher. So far, so good...
The problem is... Super alone is used in Unity to show the Launcher! So when you Super+Tab, then release Tab (or let both pressed for a while), Super will trigger the launcher and "steal" the focus away from the ring/shift switcher, so they won't detect they key release and thus not will not select the current window.
And there are 2 solutions to solve the conflict. You either:
- Disable Unity's
Key to show the Launcher, or remap it away from Super
Set Shift (or Ring) Switcher to use a different combination other than Super+Tab, something that does not use Super.
An obvious combo would be Alt+Tab itself, provided you also disable all
Key to start the switcher... key bindings in Unity's Switcher settings. Or, as a "sweet revenge", map them to use Super instead of Alt :P
Personally I prefer the latter, since tapping Super to open the dash is very useful, and there is no other dead key so easily available for that.
I can provide some screenshots to help if anyone finds this useful.