using ubuntu fiesty.its very annoying to move mouse or tap a key in middle of games.(frozen bubble especially)
press alt+f2 to get run dialog -inside type : "killall gnome-screensaver"
without quotes(").or better if u dont want screensaver u can uninstall gnome-screensaver from apt or synaptic gui manager from System>admin>synaptic.
system> prefs > screensaver and disable it rather than uninstalling it.
is that the only way? cant it not start screensaver while using joystick just like mouse and keyboard