[PATCH 0/2] Fixing screen crossing for Zaphod

[Peter Hutterer]

Handling of multiple ScreenRecs is still an issue.
We've had a problem for several years now where absolute devices get
stuck on the right-most screen [1]

This is basically just a scaling bug that can be fixed by extending the
scaling range from 0...width to -1..width. This still gives us bad behaviour
as the absolute device is then bound to the screen until it triggers the
screen change - different to the behaviour of abs devices in RandR setups
(device scaled to desktop).

One of the problems this is obvious is if you have multi-headed
Xephyr/Xnest/spice setups. You can't just move into window X and expect the
pointer to be there, you'd need to trigger the screen change on each side
first.

So, patch 2 simply changes the screen scaling to desktop-with scaling,
albeit not in the most efficient manner. This way the behaviour of absolute
devices is the same as in RandR setups and we can then use the
transformation matrix to bind to a specific screen.

Cheers,
  Peter

[1] https://bugs.freedesktop.org/show_bug.cgi?id=25182