Hi Edwin, thanks for following this discussion! I got the impression that XCOM uses invalid or at least undefined behavior from comment 88, 91 and 92, and from the apitrace bug comments here: https://github.com/apitrace/apitrace/issues/407#issuecomment-166619366 https://github.com/apitrace/apitrace/issues/407#issuecomment-166752457 https://github.com/apitrace/apitrace/issues/407#issuecomment-167866502 But I'm no OpenGL developer, so I'll let Nicolai or Jose or somebody else knowledgeable confirm or refute this :)