limit background process more

[dmgr]

I think it would be a great idea to set two limits (for xwindow applications), one when the application is in foreground and the other when is in background.

For example when firefox is not active application, we could limit it to 1%, when is active, limit could be higher, eg. 30%.

https://bbs.archlinux.org/viewtopic.php?pid=919624