plt/racket — pull request #321 by tonyg (2013-04-18 16:42:18+00:00)
Title: On Linux, failure to load libgdkglext-x11-1.0 or libgtkglext-x11-1.0 is silent

It's very difficult to debug a GL failure when this happens, so the patch here simply calls log-warning to provide some clue to the clueful user that they might need to apt-get install libgtkglext1.