I'm trying to enable GLX_EXT_texture_from_pixmap in direct rendering
for swrast. After applying patches given in this thread glxinfo shows
TFP on GLX extensions string, but correlated functions don't work.
1) I found that GetGLXDRIDrawable() inside drisw_bind_tex_image()
returns NULL, so
It was mentioned in commit 8d789be03430b80e0ba2fef19d56dd0b8e699ea2
that gnome-shell could run on the classic swrast driver with the
__DRItexBuffer extension added--but when I compile Mesa git and use
the swrast driver, glxinfo doesn't show GLX_EXT_texture_from_pixmap as
enabled, and Ubuntu 10.04
