Currently MP2 Client window supports 3 states, which you can toggle by ALT-ENTER:

1. Fullscreen
2. Windowed
3. Windowed "Always On Top"

Separate the "Always On Top" mode into a different shortcut to avoid user confusion about 3rd state.

https://forum.team-mediaportal.com/threads/mp2-898-porting-mp2-to-net-6.140089/page-25#post-1294292