[PATCH 2/2] protocol: add state set functions for maximized and fullscreen.

Jason Ekstrand jason at jlekstrand.net
Sat Nov 2 16:50:40 CET 2013

On Fri, Nov 1, 2013 at 11:36 PM, Jasper St. Pierre <jstpierre at mecheye.net>wrote:

> On Fri, Nov 1, 2013 at 11:58 PM, Jason Ekstrand <jason at jlekstrand.net>wrote:
> ... snip
>> Gregory,
>> Thank you very much for your e-mail.  I think that helps a lot.  The lack
>> of code is ok because I think Rafael is planning to start implementing as
>> soon as things settle a bit.  Sometimes protocol discussions can end up
>> with a whole lot of hypotheticals and what you gave was a very clear
>> concise discussion of the topic.
>> If I am understanding you correctly, what we need are an "activate"
>> request and "notify_active" and "notify_inactive" events.  To support
>> sloppy focus, clients should just always try to activate on
>> wl_pointer.enter and let the compositor sort it out unless they have a good
>> reason to do otherwise.  For cases such as alt-tab, or another window
>> closing, the compositor simply sends a notify_active.  I think I'm ok with
>> this.
>> Two more questions that come to mind:
>> 1) Will we ever need a deactivate request?  Under the given scheme, no
>> need comes immediately to mind.
> No. Well, if we need it, let's add it later.
> 2) Should the activate be associated with a particular seat.  If you have
>> multiple cursors, you can easily have multiple active windows so this seems
>> perfectly reasonable.  If this is the case, should this be part of wl_seat
>> or should we keep it in xdg_shell?  I'm a little afraid to clutter wl_seat
>> unnecessarily but this is very quickly starting to look like a seat focus.
> I don't think windows need to know which seat they're active on, only that
> they're active on possibly one of them. From my eyes, there's nothing that
> prevents the compositor to send "notify_active" to more than one window at
> the same time for multiseat support.
> If I click on an unresponsive window A, we'll send a "click" event to that
> window, but since it's unresponsive, it won't activate. I might then decide
> to activate another window B, which will respond. When the window A becomes
> responsive again, it will process the "click" event and decide to send an
> "activate" request back. We need to make sure that this "rogue" client
> doesn't steal the focus, so the compositor needs to record the serial for
> the last "activate" event it got (sent by window B), and compare against it
> when it gets an "activate" event, besides whatever policies it might have.

Here is the problem.  Say you have two pointers P and Q and two and two
windows A and B.  P clicks on A and A a is now active.  Q clicks on B and
now B is active.  Then P goes and clicks on B.  However, B is already
active so it doesn't request an activation and A stays active with pointer
P.  This assumes we are trusting clients to request activation.  The other
option is that we simply force a click-always-activates model and clients
are constantly fighting the compositor just to make modal dialogues work.

> But serials are seat-specific, so we need the "activate" request to relay
> the seat back for the purposes of validating the timestamp. I don't think
> it makes sense to expose the active window on wl_seat, though.

That's not correct.  Timestamps are seat specific but timestamps are not
the same as serials.  Timestamps are local to the seat.  Serials are
actually compositor-global in weston and, in order to make things work,
should probably at least be client-global in other compositors.

> Once again, Gregory, Thanks for the explanation.  I hope I'm following ok.
>> --Jason Ekstrand
>> _______________________________________________
>> wayland-devel mailing list
>> wayland-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/wayland-devel
> --
>   Jasper
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