Commit 4f2bb583bf changed things so that the compositor used
clutter_threads_add_repaint_func_full (CLUTTER_REPAINT_FLAGS_POST_PAINT
to get after-paint notification and send _NET_WM_FRAME_DRAWN, but this
doesn't actually work, since Clutter will already have blocked for
VBlank before calling post-paint functions.
The result is that frame synced toolkits like GTK 3.8 will normally
only be able to draw every other frame.
Since ::paint doesn't work either, a new function
clutter_stage_set_paint_callback() has been added to Clutter
(and will be included in the 1.14 branch)
https://bugzilla.gnome.org/show_bug.cgi?id=698794
XInput 2.3 adds support for "barrier events", which let us know when
a pointer barrier has been hit, and when the pointer has stopped
hitting the barrier, and lets us "release" the barrier, temporarily
letting the pointer pass through the barrier. These features can be
combined to allow for certain pointer gestures, such as "pushing"
against the bottom of the screen, or stopping the pointer on monitor
edges while dragging slowly for increased edge precision.
This commit should allow graceful fallback if servers with
XInput 2.3 aren't supported.
https://bugzilla.gnome.org/show_bug.cgi?id=677215
