I have a side project going which you may be interested in. It is a
lightweight window manager in the spirit of the OS X WindowServer.
I wanted to create a new backend for gnustep that doesn't use X11. I too,
originally thought of using DirectFB as the basis, but IMHO directFB is
rapidly developing into something way beyond a simple lightweight window
manager. So, I started NuVu
http://www.sf.net/projects/nuvu
(Source is available via CVS)
It is written in almost completely inlined C++ and uses STL for speed and
easy development. Being a lightweight window server/manager, it does not
draw anything to the screen (well, it does do blits with transparency).
Instead, it allocates a piece of shared memory which the client also has
access to. The client "draws" to this shared memory, then tells the server
it is done drawing. The server then blits it to screen (it's a little more
involved, but that's the basics). As far as the mechanics of actual
client/server communication, I haven't coded anything yet, I'm thinking
about what would be the best method.
Oh, nuVu uses the Linux video frame buffers. But I'm sure you guessed that
already.
You might be interested in helping with this project, as it's main purpose
is to be the basis for yet another gnustep-backend.
Chad