try to fix again

Calculate x and y of usable_area, not just width and heigth.

fix multi monitors

If you don't recalculate the monitor's geometry before arranging,
clients get arranged in the first monitor. I don't understand why this
fixes the bug since tile() uses m->w rather than m->m, nor why it needs
to be recalculated after creating the monitor but sway does it too.

Although not necessary to fix the bug I also made arrangelayer() do like
sway again and recalculate usable_area instead of reusing m->m, since
m->m seems to be incorrect until it gets recalculated shortly after in
arrange(), so I suspect that leaving usable_area = m->m will cause
issues under certain circumstances.

Someone with a multi-monitor setup or better knowledge of Wayland may be
able to figure out the cause of the bug. For now, this makes layer shell
work.

remove variable

use size_t for lengths

rename variable and merge 2 lines

simplify

use unsigned int for loop indexes

Don't let overlays lose focus

if you open a new window while an overlay is mapped, the overlay should
stay focused

fix restoring pointer focus

I don't know why I thought it was working before. Maybe I should go do
something else.

improve code style

remove comment

I don't know why it wasn't working before but now it does ¯\(ツ)/¯
(it wasn't caused by the just removed code either)

remove mysterious code

Why would a surface that's not keyboard interactive get focused? Let's
remove this for now and see if issues arise.

focus the previous client in the similar code too

refocus old client

When a layer surface is destroyed focus should be returned to the last
client. Luckily if there are multiple overlays the previous overlay
still gets focused.

fix alhpabetical order

simplify focus leave condition

reuse motionnotify()

enable pointer on layer surfaces

more TODOs

fix focus leave condition

needs refactoring and testing