[root@localhost ~]# fgl_glxgears
Using GLX_SGIX_pbuffer
X Error of failed request:  GLXUnsupportedPrivateRequest
  Major opcode of failed request:  143 (GLX)
  Minor opcode of failed request:  16 (X_GLXVendorPrivate)
  Serial number of failed request:  27
  Current serial number in output stream:  29