Xfwm4 doesn't seem to disable window composition when the application window sets _NET_WM_BYPASS_COMPOSITOR flag. The freedesktop WM specification http://cgit.freedesktop.org/xdg/xdg-specs/tree/wm-spec/wm-spec.xml#n1579 states that _NET_WM_BYPASS_COMPOSITOR could be set by the client to request uncomposited window. Mutter is compatible and Kwin will be soon (https://git.reviewboard.kde.org/r/126561/) Thanks !
I still hope that will be implemented one day because it's so useful !
yes, I reckon adding this would be fairly simple
Ping?
Adding the option is the easy part, un-redirecting windows as well, but once you have unredirected the windows that request _NET_WM_BYPASS_COMPOSITOR, they will most likely not appear at all because they will be covered by the COW (compositor overlay window). So you'd had to shape the COW somehow to let the non-redirected windows see through, which is not trivial and possibly slow. The spec stated that the compositing manager must not bypass compositing of the window if it would cause differences from the composited appearance, but that's to me sounds like an over simplification because you may have drop shadows from other windows or even a semi-transparent windows from another client on top, and this wouldn't work even though the appearance of the window itself is not changed. I am not convinced that mixing redirected and unredirected windows is a good idea. I reckon the only case where this would make sense, is with fullscreen windows on top of the stack.
(In reply to Olivier Fourdan from comment #4) > I am not convinced that mixing redirected and unredirected windows is a good > idea. I reckon the only case where this would make sense, is with fullscreen > windows on top of the stack. Only fullscreen windows are unredirected on Mutter AFAIK (meta_surface_actor_x11_should_unredirect(), src/compositor/meta-surface-actor-x11.c).
Can it be implemented for 4.14 ? At least for fullscreen windows since it doesn't really make sense for windowed one ? It is a rellly useful feature. Thanks !
Even more useful now that Google Chrome implement it too ! https://bugs.chromium.org/p/chromium/issues/detail?id=344141#c48
xfwm does not have auto unredirect heuristics that compiz and mutter have, that Chromium bug does not affect xfwm really.
It can affect you if you enable the unredirect fullscreen windows option.
RetroArch related bug: https://github.com/libretro/RetroArch/pull/6493#issuecomment-378082506
Olivier Fourdan referenced this bugreport in commit 642275e9d795e9f2cba78df7e3e92485955638a6 compositor: Add support for NET_WM_BYPASS_COMPOSITOR https://git.xfce.org/xfce/xfwm4/commit?id=642275e9d795e9f2cba78df7e3e92485955638a6
Awesome, Thanks !
Thanks Olivier! It would be great have a new development release (4.13.1 ?) to help testing!