As far as I'm aware this just works, I'm not aware of any open issues related
to it.

Since we already implement it. Tweening will likely never work with fixed
function GL.

We can just do this in context_create_fbo_entry() now.

The draw buffer handling code depends on this being current. This fixes a bug
exposed by commit 075fa654.

kernel32: Add a test to show that a process with a not closed handle to an already terminated thread fails to terminate cleanly.