plugin-taskbar: show app under wayland

[hepuyao]

Log in to the plasma-wayland desktop environment. Start lxqt-panel. Run mpv *.mp4 in the terminal. As a result, the taskbar plugin does not display the icon of the mpv player.

can lxqt-panel display wayland apps?

[tsujan]

I haven't tested lxqt-panel under Plasma (yet) but I know that LXQt's icon handling isn't compatible with that of Plasma/KDE and can't be loaded there (Plasma crashed when I loaded it a year ago -- not LXQt's fault). That may be the reason, although I can't be sure for now.

[elviosak]

No, taskbar only shows icons from X11 windows.

[tsujan]

No, taskbar only shows icons from X11 windows.

So, there's no problem with LXQt's taksbar icons under Plasma+X11? If so, there may be a bug somewhere. That's worth checking the code.

[tsujan]

The task button finds its icon by using KWindowInfo::windowClassClass() and, if not found, KWindowSystem::icon(), both of which belong to KWindowSystem, which is a tier-1 KDE dependency of LXQt (actually, an extension of Qt). So, the icon shouldn't be specific to X11.

The problem you see may be caused by something else but I have no idea what. Anyway, the issue is kept open for now.

[elviosak]

i thought KWindowSystem was only a higher level xcb API and only supports X11, but now i'm not sure, KWindowSystem has almost no mention of Wayland and mentions X11 a lot, but also doesn't say it's only for X11.

I found some stuff on plasma-workspace:
https://github.com/KDE/plasma-workspace/blob/a5c7df39460eff7454f992a2307753bfb1eb095f/libtaskmanager/xwindowtasksmodel.cpp

https://github.com/KDE/plasma-workspace/blob/a5c7df39460eff7454f992a2307753bfb1eb095f/libtaskmanager/waylandtasksmodel.cpp

the X version uses KWindowSystem for window events, and the Wayland version uses KWayland.

[tsujan]

Perhaps the goal was making it work under both X11 and Wayland, at least with KDE. For example, I know for sure that KWindowEffects works with KWin under X11 and Wayland alike (I've used it in Kvantum's blur helper with Qt ≥ 5.11 and without X11 dependency). But I've also tested and seen that KWindowSystem knows nothing about virtual desktops of Plasma-Wayland.

Based on these, I've assumed that the project is still incomplete.

[elviosak]

@tsujan i found this, it confirms KWindowSystem doesn't work with wayland...

from https://api.kde.org/frameworks/

[tsujan]

@slidinghotdog, thanks!

The documentation should be incomplete because I'm sure KWindowEffects works with KWin under Wayland.

It smells of indecision.

[tsujan]

Out of our control. There's no way of doing it independently of the Wayland compositor; only one of so many Wayland hassles. Closing...

[stefonarch]

Maybe we should reopen this, a taskmanager based on https://wayland.app/protocols/wlr-foreign-toplevel-management-unstable-v1 will work in any compositor, except kwin, which supposes that we would need 2 different taskmanager, one for kwin_wayland and a generic.
The lack of support for this protocol in KDE is also the main cause why kwin_wayland isn't really usable atm.