Is it possible to add a new feature/setting where when a fullscreen program(except screensaver) is running BOINC would suspend any works that is running at the time?

That would come in handly for people who reguarly play BluRay or any other HD video on their computers, where those tasks require intensive computation.

"Suspend work while computer is in use" would not work well in this scenario because video playing does not require mouse or keyboard interaction.

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Such an option is already available, for use with games, media players and just about anything you don't want BOINC to interfere in. It's available since BOINC 6.4

You can have a cc_config.xml in your BOINC Data directory that will suspend your BOINC (under Windows only, I'm afraid) automatically when any of the exclusive applications you told it to look out for is detected in main memory. (*)

To do so, set up the cc_config.xml file with the following options (example of my cc_config.xml):

<cc_config>
  <options>
     <exclusive_app>Spybot.exe</exclusive_app>
     <exclusive_app>Crysis.exe</exclusive_app>
     <exclusive_app>Winamp.exe</exclusive_app>
     <exclusive_app>Mplayer.exe</exclusive_app>
  </options>
</cc_config>  

You only need to tell what application name it needs to look out for, no need for the full path to the name. If you already have one, you can add the <options></options> part to your existing cc_config.xml file.

Watch out with launcher files. For example, Fallout 3 uses the Fallout 3 Launcher, which does not stay in memory after you launched the game. So do not use the launcher file as the exclusive app, but the game executable's name instead. I have tested this with the Oblivion launcher as well, here it is the other way around. If you add the Oblivion executable only, BOINC will not suspend. You will have to use the Oblivion Launcher name.

(*) There is a problem when you have your preferences set to Leave applications in memory while suspended. Any task still in the video card's RAM will stay there until you resume BOINC. Although it will not use your GPU, the amount of memory that a Seti CUDA tasks takes up (200MB+ of the VRAM) may still have impact on your other activities.

BOINC 6.6 will unload the task from video memory when you suspend BOINC and the task has at least checkpointed once.

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