Taskmanager: opening menu (dash/kicker/kickoff) triggers "plasma task" being shortly visible in taskmanager sometimes

[star-buck]

No description provided.

[bhush9]

Upstream bug : https://bugs.kde.org/show_bug.cgi?id=332024

I think it is not specific to kicker/kickoff but all plasma dialogs.. and AFAIU it is RESOLVED WAYLAND.

[star-buck]

yes, but that shouldn't mean it could be resolved non-wayland too for the time until then.

[star-buck]

@eikehein : any idea to fix this (especially on an arm odroid it happens all the time very visibly)?

[eikehein]

I think last time I talked with Martin about this his conclusion was "not before Wayland", but I'll brainstorm again - imho it's a Qt bug (basically the window properties like SkipTaskbar are now applied after show(), you can't set them before anymore because show() will ignore/overwrite the state - which is super stupid in my book), so it depends on how hard we want to fight the windmills on getting it changed perhaps

[star-buck]

we need a workaround for the time until wayland ever gets accepted and shipped default (like 1-2 years).

[eikehein]

(In unrelated and more positive news, I fixed the icon flicker recently so one of our two long-standing TM annoyances are gone :)

[davidedmundson]

I now know exactly what's happening. Which is good. I'll write it here in case I get distracted tomorrow.

WM_STATE contains a list of atoms. Including skip_taskbar
https://specifications.freedesktop.org/wm-spec/wm-spec-1.3.html#idm140130317598336

Qt supports a subset of possible window states (windowFlags), but it does not support skip_taskbar so we try and set that ourselves .

In order to not have a flicker we need skip_taskbar set as a state before the window is mapped.
However, if we set it before QWindow::show() it gets reset. by Qt just before it shows the window.
If we set it afterwards, it's too late.

This reset happens in
QXcbWindow::updateNetWmStateBeforeMap
which calls
QXcbWindow::setNetWmStates(NetWmStates states)
which calls
xcb_change_property with XCB_PROP_MODE_REPLACE with only the atoms Qt supports.

Dialog has a current hack that sets the flag afterwards, but it's done in a rather silly way, so I suspect the author didn't really understand the problem, just found something that sort of worked.

I can do a workaround that makes Plasma popups behave better (but won't fix krunner flickering there).

The proper fix will /have/ to be in Qt, but it should be possible.

[davidedmundson]

Added a workaround, which will fix the most common case.
https://git.reviewboard.kde.org/r/127374/

[star-buck]

Can you state target (package) and ETA for expected next release?

[davidedmundson]

workaround that fixed plasma popups:
plasma-framework,
ETA first week of April.

[star-buck]

Version would be Frameworks 5.21?

[eikehein]

^ Yes, based on positive reviews for the patch + 5.21 is the next release, scheduled for early April.

[star-buck]

seems to be fixed

[star-buck]

still visible in plasma 5.8 with latest qt5.7 and frameworks 5.27, therefore reopening

[eikehein]

What system does this happen on? We have no one left who can reproduce this at all (last person was Bhushan).

[star-buck]

Latest plasma5.8, qt5.7, kf5.26 ( i could make a video of the taskmanager showing a task when opening menu, but then i hope i dont need to just for the sake of it ). Best is to download maui2 iso based on neon and try to reproduce under vbox or real hardware, will post link on irc or here shortly.

[star-buck]

added info:
it does indeed seem to happen only with Dash Menu, no longer with Kicker.

[eikehein]

Fix for Dash under review at https://phabricator.kde.org/D3020

[eikehein]

Patch pushed, should be in 5.8.1