wl_surface/wl_subsurface composition

[Martin Stransky]

Hi guys,

while solving a Firefox Wayland bug [1] I wonder if there's any 
composition between a surface and a subsurface on compositor side 
(namely mutter) when the subsurface area is subset of the surface and 
the surface is set as opaque.

Both surface and subsurface are using ARGB pixel format.

Thanks,
Martin

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1591489#c9

-- 
Martin Stransky
Software Engineer / Red Hat, Inc