I would definitely vote yes to re-enabling the screensaver when playback stopped.
I also think there may be a bug somewhere because I've tried switching it into windowed mode after playing something in order to get the screensaver to kick in and it doesn't (or doesn't always - haven't done a lot of testing).
Note that all of these display mode changes are occurring via IRMAN commands using your plug-in. Ideally from my perspective the way things would work would be:
1. Media Center idle in fullscreen mode = screensaver enabled
2. "Display" button pressed on remote to bring up hairstyle = screensaver disabled
3. Playback started, fullscreen mode = screensaver disabled
4. Playback stopped, fullscreen mode = screensaver re-enabled.
Right now it's a bit frustrating because I'd like to leave MC running at all times but instead what I do is shut it down when finished playing stuff. Since the PC is in the basement (TV in living room) this means I either have to go downstairs to launch it or use RealVNC to remotely start it via my notebook. Blech.
-Adam