[SDL] SDL 1.3 and rendering API state management

[Ryan C. Gordon]

> A simple solution would be some kind of mutual notification interface, 
> so that SDL renderers can tell the application when they've messed 
> with the API state, and vice versa.

Alternately, you can use glPushAttrib().

I don't think SDL should make _any_ promises about what it will or won't 
touch in the GL stack if you are only using SDL's 2D facilities. Nor do 
I think that any add-on library should be changing GL state between 
calls. If you want to draw something, set your state, push some 
polygons, and set the state back. Otherwise, you're talking about 
locking down a fairly complicated set of promises (or specifying a 
fairly complicated set of notification APIs).

--ryan.