gnome-desktop3 string freeze exception request

[Christopher James Halse Rogers]

Bug https://bugs.launchpad.net/ubuntu/+source/compiz/+bug/824099
requests a string freeze exception request for gnome-desktop3's XRandR
support.  The workaround for this bug requires that gnome-desktop
refuses to configure a multi-head display with a size exceeding
GL_MAX_TEXTURE_SIZE when Unity is running.  This requires a new error
message in gnome-rr-config.c, which will be shown to the user,
explaining why their configuration request has been rejected and what
they can do about it.

Thanks,
Chris Halse Rogers.