xdg-shell: about configure, states and ack_configure

[Olivier Fourdan]

Hi all,

Following the discussion around the min/max size addition to xdg-shell v6, I would like to get one point about configure events clarified, if possible.

First, a quick reminder of what the spec currently says:

1. configure: 

    The configure event asks the client to resize its surface or to
    change its state.

    The width and height arguments specify a hint to the window
    about how its surface should be resized in window geometry
    coordinates. See set_window_geometry.

2. state:

    The surface is maximized. The window geometry specified in the
    configure event must be obeyed by the client.

    The surface is fullscreen. The window geometry specified in the
    configure event must be obeyed by the client.

3. ack_configure:

    When a configure event is received, if a client commits the
    surface in response to the configure event, then the client
    must make an ack_configure request sometime before the commit
    request, passing along the serial of the configure event.

   and also:

    The compositor expects that the most recently received
    ack_configure request at the time of a commit indicates which
    configure event the client is responding to.

So, for example, if the compositor sets a state maximized and a size larger than the client would expect, in theory, the client could ignore the request, not configure its surface and never send an ack_configure for that serial.

At least, that was my understanding and that's why I reckoned the client would always have the final word even if the compositor would not follow the min/max size hints.

Thus my questions:

 - Is my understanding of the spec accurate?
 - Is the current wording of the spec clear enough?
 - If not, should the spec explicitely state that the client may chose not to ack a configure event?
 - And at last, is "not sending an ack" the same as "not acking", ie should we add the notion of "nack_configure"?

Cheers,
Olivier