[PATCH 0/8] backing store Always support, v2

[Adam Jackson]

Much the same as the previous series, with review feedback merged.

This regresses xts' XMapWindow/13 and XMapSubWindows/12.  XMapWindow/13
creates a WhenMapped window with one child, maps the child, and then maps
the parent.  The ensuing expose events for the parent clip out the region
of the child, when the protocol says it should be the whole parent
(because we are "newly maintaining" backing store due to the map).   The
MapSubWindows failure is analogous.  There may be other issues lurking.

- ajax