[PATCH wayland v2] protocol: define the concept of wl_surface role

[Bill Spitzak]

On 08/19/2014 12:29 AM, Pekka Paalanen wrote:

> +      Often, this
> +      request also creates a new protocol object that represents the
> +      role and adds additional functionality to wl_surface. When a
> +      client wants to destroy a wl_surface, they must destroy this 'role
> +      object' before the wl_surface.

Destroying the last protocol object for the role does not remove the 
role, correct? The client can recreate a new protocol object for that 
role and it still works?

> +      Losing a role means losing all the role-specific state.

I'm not sure what you are saying here. I think maybe you are talking 
about a surface that was used for drag & drop when the drag & drop ends?

I thought in that case the surface must be destroyed: ie once a surface 
"loses a role" it cannot be assigned any role, including the same one. 
But in that case the "state" is irrelevant.

Are you allowed to reuse the drag & drop surface for another drag & 
drop? If the creation request also sets some state it is obvious that 
portion of the state is not preserved. But it seems a lot easier on both 
clients and compositors if other state is allowed to be preserved.

In any case I find this sentence really confusing. Also it might help if 
there was a concrete example of a surface "losing a role".