In testdyngl.c the event type was being anded (&) with SDL_KEYDOWN and if the result was none zero the program was quiting. This is very weird because it was

working earlier this week.

I added some more trace code to SDL_x11events.c

In SDL_X11opengl.c I modified SDL_GL_GetSwapInterval() so that it returns a pretty good value even if you have the SGI swap extension instead of the MESA swap
extension. I just saved the value you set and return it too you.

test/testdyngl.c

@@ -180,7 +180,7 @@ main(int argc, char *argv[])
         SDL_GL_SwapBuffers();
 
         while (SDL_PollEvent(&event)) {
-            if (event.type & SDL_KEYDOWN)
+            if (event.type == SDL_KEYDOWN)
                 done = 1;
         }