Run caffeine ONLY when using fullscreen

[xorgx3]

Hi,

I want block my DPMS only when I watching something in fullscreen(eg Youtube). Unfortunetely i don't know how it doing. Now I have to add chromium browser, but it's nuisance.

It's possible to do it? Of course I set "activate for flash videos" but isn't working.

I am using Arch Linux, Chromium and Openbox as window menager.

Please help me(or maybe are another programs/scripts for that)?