(opening bugzilla RFE per yosh's suggestion)

I've got a patch that extends the linux-fb gdk backend to handle rendering
to a generic buffer (32-bit RGBA buffer).  "extends" is used loosely here,
because the majority of the worked involved ripping out linuxfb
handling/setup, ripping out mouse drivers and keyboard input drivers, and
hardcoding a 32bpp truecolor visual.

I have the code pulled out in a separate "gl" subdirectory of gdk; mostly
copies of linux-fb, with some heavy changes in keyboard/mouse input
handling.  Keyboard and mouse input comes in via a GQueue protected by a
GMutex, which is polled via a GSource in the main loop.. keyboard input
uses SDL keysyms, for simplicity (thus there's a build-time dependency on a
SDL include file atm).

What this gives me is the ability to use gtk as a UI on top of an OpenGL
scene (or, presumably, Direct3D or just about anything where I can render
an image to the screen).  There are very few UI packages that can do this;
the ones that are out there generally suck.  There are no polished
middleware packages for this.

I'll attach a patch against 2.3.1, but it duplicates a lot of linux-fb
code.  Any suggestions on merging the two, or any feedback on the chances
of this type of gdk support making it into mainline gtk would be
appreciated. :)