Preventing Screen-lock/Screen-saver under Ubuntu (Linux) with controller?

[Cyba Cowboy]

Most games - including other games available via Steam - will prevent Ubuntu's lock-screen or scren-saver from kicking-in whilst the game is in-use... However with regards to Portal, this is not the case when one is using a controller (in my case, the Sony DUALSHOCK4) to play the game.

In fact, Ubuntu will often lock the screen mid-game whilst I am playing Portal, forcing me to unlock the screen and then switch (Alt+Tab) back into my game!

This is really, really frustrating, so any help preventing this would be appreciated...

[RudeBoy]

This issue affects me too. I turned off the screensaver. Any better tip?
I'm using a Xbox360 Wired controller. I used to play with a wireless Xbox360 controller along with Big Picture mode and this hadn't ocurred.