>IIRC wl_shell is not defined to be double buffered. Not sure how it's about xdg. There is always the chance of breaking things *cough*Qt*cough* when changing that - even if it is sane.
Xdg definitely is and for v7 this is important as mapping/unmapping is different. * committing a surface with empty buffer on a surface unmaps a window * commiting again (still with an empty buffer) tells the compositor we're going to send a configure event because we're about to remap the window which means we need to be at least be tracking the wl_surface changes even if we don't properly double buffer. >From a Kwin POV, it'd be best to deal with this on the kwayland side as we need to reset the xdg_toplevel state. Personally I think deleting the xdgshellsurface in Qt is a lot less messy than the new XDG. The only thing that doesn't make sense is deleting the wl_surface. I wrote a patch that does that. https://paste.kde.org/pgh8jafqw That works fine for XDG, but wl-shellsurface doesn't like that and remains until you delete the wl_surface. wl_shell_surface_destroy literally sends nothing in wayland_debug. I think that's why they end up deleting both. It's not a simple thing to abstract when everything behaves so differently. > What could be an idea is to not do anything in KWin till we get the first > map event. That is evaluate all the shell options only on map. > > >> In practice that won't acheive anything as QWaylandWindow::initWindow >> calls commit a few times randomly before the expose event that we're >> currently hooking into is called. Also kwayland-integration calls >> commit on the surface every time it attaches something, which I don't >> think is right. >> > > It is fine given the definition of the interfaces. We setup some state and > commit it. If we don't commit we don't know when that will happen. We only > adjusted our own relevant states and everything else is not affected. > That would be true if we weren't using these in hooks in the middle of Qt adjusting things. Maybe avoiding that is the right fix though. ---- FWIW I'm meeting Jonas (the XDGShell and scaling guy) in two weeks at Guadec.
