While the window geometry overlay is centered inside the tile overlay
neither the text nor the location change, so there is no need to
re-render and update it every time the window moves.
Keep track of areas that overlays were rendered to when we recompute
occlusions. This allows us to then easily figure out areas where
overlays were moved from or removed from.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
This creates a 2-dimensional array of WindowStack instances, one for
each virtual desktop. The main desktop 0,0 is the main desktop, which
is the desktop used for all stationary windows (e.g. taskbar, desktop).
When adding windows to a desktop, stationary windows are always added
to the main desktop.
When composing the desktop, there are usually two WindowStacks
involved. For stationary windows, the main desktop will be traversed,
and for everything else the current virtual desktop will be iterated.
Iteration is interweaved to preserve the correct order. During the
transition animation, two WindowStacks will be iterated at the same
time.
This fixes a regression where the geometry label isn't updating even
though the window geometry had changed because the geometry label's
location isn't changing.
An Overlay is similar to a transparent window, but has less overhead
and does not get rendered within the window stack. Basically, the area
that an Overlay occupies forces transparency rendering for any window
underneath, which allows us to render them flicker-free.
This also adds a new API that allows displaying the screen numbers,
e.g. while the user configures the screen layout in DisplaySettings
Because other things like drag&drop or the window-size label are not
yet converted to use this new mechanism, they will be drawn over the
screen-number currently.
