GTK draws its own (double) window decorations under Mir

Many gtk applications are moving towards client side decorations in order to put widgets into their title bars. We'd like to stop patching them (upstream or downstream) with the move to Mir and Unity 8, as that is a break in design anyways and many of the newly designed default applications will use client side decorations as well.

Do we really still need the csd/ssd duality or could we just let all apps draw their decorations themselves?

Sure Mir will/should support client-side decorations.

The best suggestion I have right now is:
  1. You set mir_surface_type_freestyle
  2. Wait for Mir shells to honour the surface type and not wrap extra decorations around it.

In future we might have some additional attribute you could set for client-side decorations instead of mir_surface_type_freestyle. Not sure...

Clarification: By decorations I mean the "physical" window extents and not shadows.

AFAIK we have no plan to allow for client-side shadows (ie. rendering beyond the physical snapping extents of the window).

Of course Mir can't know if you're painting shadows or not. Just your window placement will look wrong if you do that bit yourself.

Server-side shadows will look more consistent (in size and gradient) and allow us to do proper 3D shadows in future too.

Added a Mir task - we need to honour the surface type and avoid title bars on certain types.