It seems that with the latest intel drivers when multi-texturing using an RGB
TFP texture, the texture is being setup internally as an RGBA texture, where
the alpha channel is mostly 0.0 so you only see a shimmer of the window. This
workaround forcibly defines the alpha channel as 1.0. Maybe there is some
clutter/cogl state that is interacting with this that is being overlooked,
but for now this seems to work. (Tested on i945 + DRI2)
Before we've retrieved a pixmap for a window, the shaped texture
has a 0x0 texture, which will cause mutter_shaped_texture_ensure_mask()
to crash. Just skip all of paint/pick in this case.
http://bugzilla.openedhand.com/show_bug.cgi?id=1283