Code review comment for lp:~andreas-pokorny/mir/allow-transparent-server-buffers

1. ok.. just that coding guideline state 120 and there was already lots of code in that length

4. Should it have any specific functionality other than picking a different pixel format?

8. Behavior change so far is only working inside nested - the other platforms ignore the policies more or less. Mesa needs fixing if now somebody tries to create a non nesting shell with alpha channel it will not get a buffer.