Is there an easy way to detect when the screen has been blanked, say after
an xset timeout, or the activation of a blank screensaver? Basically, I
have a shell script that I want to run when the screen is blank. An
alternative would be to check the keyboard + mouse idle time (the trigger
for blanking), but I don't know how to do that either. If there's a simple
(ie not involving C-coding!) way to do that, that would be fine instead.
At the moment, I'm just getting the idle time from the output of `who -i',
but that is not very satisfactory as it only checks terminals, and not
activity in Emacs windows, for example.