Intermediate commit (it works, bitches!).

... actually I don't know - I just managed to handle two displays
separately correctly about two minutes ago, but it crashed after I moved
to the same workspace with both monitors under some circumstances that I
am yet unable to grasp.

But I still thought this is worth a commit (the code is so chaotic the
diffs don't tell anything useful anyway).

Anyway, stay tuned for a more definite commit tomorrow, I'm going to
sleep.