I've been playing around with egl_glx lately and noticed it was missing something I wanted. A quick look at source revealed it'd be an easy addition. This is my first time contributing to Mesa. Honestly, I tried setting up a Mesa dev environment, but I never quite got it working. That shouldn't make my code go to waste though! I was hoping someone could take a look at the code and if you think it's sound, maybe fix any compiler errors there might be and give it a test run. There's a minor difference between how EGL handles swap intervals and how GLX_EXT_swap_control does it. The MaxSwapInterval in EGL is per-config, but GLX_EXT_swap_control does it per-drawable. My trick around this is to just assume double-buffered configs have a MaxSwapInterval of at least 1 (which is a reasonable assumption I think), and on the off chance that they don't, still report they do to the EGL user and silently ignore it.