Created attachment 26241 [details]
isolated, self-contained test-case triggering the stencil-buffer bug
Using a special stencil-buffer based technique for drawing concave polygons (e.g. font-glyphs), as also described in the OpenGL red book, causes the client to directly draw to the front-buffer, ignoring the composited enviroment (being run under compiz). Tested with kernels are 2.6.28 and 2.6.30 under Ubuntu 9.04 and Ubuntu Karmic Koala. Tested on GPUs intel GMA 945 and GMA 965 with the the xorg driver 18.104.22.168 and mesa dri "Mesa DRI Intel(R) 945GME GEM 20090326 2009Q1 RC2 x86/MMX/SSE2". An isolated and self-contained example is attached in a tarball.
*** This bug has been marked as a duplicate of bug 19174 ***
Thanks for the hint regarding bug 19174. I fixed my code and don't have the stencil buffer issue anymore. Embarrassing I used glDrawBuffer (GL_FRONT_AND_BACK) instead of just glDrawBuffer (GL_BACK).