Add idle dim switch

[danirabbit]

Fixes #168

[jeremypw]

The UI is good for changing the Gnome setting "idle-dim". However it is not really usable as it is in my opinion because both dimming and display off seem to be using the same session setting "idle-delay". So changing both happen at the same time and the dimming is never seen (as far as I can tell).

[zeebok]

The UI is good for changing the Gnome setting "idle-dim". However it is not really usable as it is in my opinion because both dimming and display off seem to be using the same session setting "idle-delay". So changing both happen at the same time and the dimming is never seen (as far as I can tell).

Oh yeah, the gnome docs use idle-delay in their explanation of how to do idle dimming. Strangely I don't see anything about idle suspending? Is there a way to make use of the idle-delay timer starting as the signal to dim? So like after 5 seconds or whatever when there is no detected input, the idle-delay timer begins and auto dimming happens?

If it means anything, it seems like on my work Macbook the screen dimming happens only a short time before locking/turning off the dispaly/suspending.