I am not sure what you mean "I suggest" but I guess, yes, it is not supposed to work since the r300 driver does not support GLX 1.3. However, it works "by dumb luck".
Upstream (mesa) seems pretty clear about the glXGetProcAddress probing being wrong. Anyway, this is an upstream (compiz) issue so I don't think any Ubuntu action is needed.
I am not sure what you mean "I suggest" but I guess, yes, it is not supposed to work since the r300 driver does not support GLX 1.3. However, it works "by dumb luck".
Upstream (mesa) seems pretty clear about the glXGetProcAddress probing being wrong. Anyway, this is an upstream (compiz) issue so I don't think any Ubuntu action is needed.