Code review comment for lp:~kdub/mir/post-if-optimizable

> It kinda is - the results of the GL composition as a Renedeable, plus a
> Cursor Renderable.
>
> This does suggest that maybe the interaction with cursor drawing needs
> thinking.
>
> None of this is blocking, just thinking.

Yeah, there's some "abstraction-defense" that needs to be done with the mesa cursor, future steps.