Code review comment for lp:~vanvugt/mir/hidden

Robert:
1. I thought about that and suggested mir_surface_state_minimized myself. But yeah I guess the use case is when a surface's contents are either not ready yet (long renders) or not presently relevant. In both of those cases, minimized is not sufficient. Because "minimized" indicates something you can restore at will (it has an icon and can be switched to). P.S. Unity has a history of not "hiding" surfaces when minimized (it overrides Compiz), so it can provide live previews of them. I never liked it, but it's a thing.

2. Yeah I see how the varying terminology might sound redundant but it's actually not. From the client API there is only one way to totally hide a surface without losing its contents. That is introduced here.
  From the server's perspective it is still useful to separate the "hidden" flag from state, because "hidden" can be true for other reasons (first frame not posted, traditional minimize or mir_surface_state_hidden).

3. Removed the "unmapped" comment.

I don't know the specifics of hikiko's use case but it all sounds reasonable to me. And as you can see, it's something we already have code for.