I know there are plans to do a complete refactor of the blender GUI system (ghost), but does anybody know if there are any plans to release it as a stand alone SDK, a-la GTK+ ?
I had an application I wanted to try to do using blender’s gui, it’s just a question of if it’ll get released, or if I manually have to take it out of the code…
GHOST doesn’t have very much to do with Blender’s GUI other than providing a window for it to appear. GHOST is a replacement for GLUT - it allows creating OpenGL windows on the various OSes, and does things like handling input events.
and man, what a mess that input method handling is 
.b
what a mess that input method handling is
agreed. I’ve seen it for myself, and it is based on:
a) defining a whole bunch of codes that represent different events
b) figuring out what to do when those events are encountered. That is spread all over the place.
Now I’m beginning to see why the interface reorganisation project has stalled for a while… 
Aligorith
GUI is the the same in 2d and 3d in the sense that your just handling a bunch of events. 3D is a bit more hassle since only if your mixing UI and 3d perspective. If your really intrested in making you own UI I’d suggest starting with 2d and migrating your code to 3d. Blender’s UI is tightly nit into blender, and GHOST is already a usable lib, you can use that on its own (there are a few standalone examples in the blender source) and start to read over blender’s ui files. It wont be an easy task, since there are a lot of states/events you’ll be trying to understand.