[PATCH weston 5/6] compositor: forbid sub-surface nesting loops

[Bill Spitzak]

Is it impossible to change the parent of an existing subsurface?

If it is possible then A<B<C and attempting to change B's parent to C 
will produce a loop and not get detected by this test since 
get_main_surface(C) is A which is not equal to B.

If this is not possible it seems pretty limiting as clients have to 
destroy and recreate surfaces to make some rearrangements.

ppaalanen at gmail.com wrote:
> From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> 
> The only way to create a sub-surface loop by recursive nesting is to
> make the main surface (which does not have a role) a sub-surface of any
> of its sub-surfaces. All other cases should already be cought.