On the other hand, display depth changes are much more disruptive, I think.
I don't think that DirectDraw can handle transfering bits from an offscreen
surface of different format than the primary surface; doing so would seem to
defeat the whole purpose of DirectDraw. My current thinking is that we will
simply display a popup message indicating that Cygwin/XFree86 will be
unavailable until the display depth is returned to the original depth.
Isn't it possible to just froget about the previous offscreen buffer and
ask all X windows to redraw themselves into the newly created surface?