The window move code needs special attention for multiple reasons:
- invalid areas for expose events need to be modified
- self-copy is not supported by Cairo
- in X11, copying from an overlapped Window might cause unexposed areas
to be copied in, spo expose events for those need to be generated.
This was all special cased in various parts of the code. By making it an
explicit vfunc, we can work around it.
Includes fixing all callers to use the cairo region API instead. This is
usually just replacing the function names, the only difference is
gdk_region_get_rectangles() being replaced by
cairo_region_num_rectangles() and cairo_region_get_rectangle() which
required a bit more work.
https://bugzilla.gnome.org/show_bug.cgi?id=613284
Make the quartz backend support the new queued translations. We do this
by keeping our own copy of the region that has been set to need display.
Using this region we can intersect by the given area, translate this and also
set needs display for the resulting area.
The X11 queue_translation operation uses NextRequest to get the serial
of the XCopyArea operation where the translation should end. However,
if the gc passed to gdk_draw_drawable has a non-flushed clip region
(which it commonly has now for the window clipping) then the next
operation will be the GC flush, not the XCopyArea.
To handle this right we now pass in the GC to be used to
queue_translation and ensure that it is flushed before calling
NextRequest().
