<div dir="ltr">Hello fellow developers, I just wanted to continue a discussion which occured some time ago, about the eventuality of adding a "xdg_surface_present()" request to XDG-Shell. (For reference, former discussion entry points are here : <a href="http://lists.freedesktop.org/archives/wayland-devel/2014-July/016078.html">http://lists.freedesktop.org/archives/wayland-devel/2014-July/016078.html</a> <a href="http://lists.freedesktop.org/archives/wayland-devel/2014-July/016224.html">http://lists.freedesktop.org/archives/wayland-devel/2014-July/016224.html</a> <a href="http://lists.freedesktop.org/archives/wayland-devel/2014-August/016269.html">http://lists.freedesktop.org/archives/wayland-devel/2014-August/016269.html</a>) To summarize : the idea behing "xdg_surface_present()" is that there are some cases where a surface wants to advertise the fact that it has been updated and the user may want to take a look (think of an IRC chat window which gets new messages containing the user's nickname). There are even some corner cases where the surface may want to be raised and focused directly ; but we do not want to request to be abused this way, a client must be prevented from stealing the focus repeatedly. At last, the compositor's shell should have the last word. Here are some of the points that were discussed and the outcomes : - Pekka Paalanen pointed out the request name was unclear and suggested to use "xdg_surface_needs/wants_attention()" instead. Jasper St. Pierre pointed out that "_NET_WM_STATE_DEMANDS_ATTENTION" already existed in X11 and does not do the same thing. We discussed that again yesterday and thought that present() fitted nicely ; - We want to implement focus stealing prevention : if the user is starting a slow app (browser...), gets back to typing a mail while it starts, and at last the browser window appears, the focus should stay in the mail window without his keyboard presses going elsewhere ; - Implementing focus stealing prevention between different clients may be easy : just count the delay between the client has been started and its shell surface actually gets mapped, and if it has been too long and the focus is elsewhere, show the surface without focusing it (but with a notification). The notion of "the client has been started" is vague, but at worst, we can use the time when the client did its initial connection to the compositor ; - Within a same client application, however, it is harder. Think of a browser where you click "new window" but lots of time pass before it appears. The "starting point" is the pointer click event. So the idea would be to pass the Wayland serial corresponding to this event : "xdg_surface_present (surface, <SERIAL>)". It the serial has been issued too long ago, do focus stealing prevention. This raises the question : how do we say "We have no serial to pass", for the standard case ? We repeatedly suggested 0 ("xdg_surface_present (surface, 0)") because serials are incrementing globals, so "0" to be issued would be very-very unlikely. Should we formalize that somewhere in the protocol ? (Having 2 requests, one with serial and one without, has been suggested by krh on IRC ; I personally prefer only one request because they would serve the same purpose, but why not ? It would get the need for formalization out of the way) We also want to secure the request from garbage random serials ; the implementation behavior is that there is only one serial valid for a few seconds, if the surface has not been focused for some time, it will not be able to raise itself even if it random()ly finds the formerly "good" serial. ----- Now the demos ! Here is the latest code : <a href="https://github.com/Tarnyko/weston-xdg_surface_present/commits/test">https://github.com/Tarnyko/weston-xdg_surface_present/commits/test</a> A video for the generic "focus stealing prevention" case (delayed start, focus stays in old surface) between different clients : <a href="https://www.youtube.com/watch?v=gifjXyPV3X4">https://www.youtube.com/watch?v=gifjXyPV3X4</a> and within the same client : <a href="https://www.youtube.com/watch?v=Xiq1p5AOf1U">https://www.youtube.com/watch?v=Xiq1p5AOf1U</a> ----- Any thoughts on this ? -- <div class="gmail_signature"><div dir="ltr">Regards, Manuel BACHMANN Tizen Project VANNES-FR </div></div> </div>