Bug 454815

Summary:	Highlight windows does not work
Product:	[Plasma] plasmashell	Reporter:	Natalie Clarius <natalie_clarius>
Component:	Task Manager and Icons-Only Task Manager widgets	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED NOT A BUG
Severity:	normal	CC:	bharadwaj.raju777, nate
Priority:	NOR
Version First Reported In:	5.24.5
Target Milestone:	1.0
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Natalie Clarius 2022-06-03 22:51:11 UTC

SUMMARY
***
The option to highlight windows when hovering over tooltips has no effect.
***

STEPS TO REPRODUCE
1. Configure Task Manager > Highlight windows when hovering over task tooltips: check
2. Hover over a task and then the task tooltip 

OBSERVED RESULT
Nothing happens

EXPECTED RESULT
Window gets highlighted

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.24.5
KDE Frameworks Version: 5.94.0
Qt Version: 5.15.4
Kernel Version: 5.17.9-arch1-1 (64-bit)
Graphics Platform: X11

ADDITIONAL INFORMATION
This only stopped working within the last months or so.

The code (src/applets/taskmanager/plugin/backend.cpp:655) makes a DBus call to a method "highlightWindows" of KWin. I 'm not well-versed with DBus and don't quite understand the syntax of the call, but I can't seem to find anything of that name browsing around in qdbus viewer. Does it maybe no longer exist?

Comment 1 Nate Graham 2022-06-06 18:03:39 UTC

It's working for me with current git master on Wayland. I wonder if we backported something wrong, or depended on a newer API in KWin that's not in 5.24.

Comment 2 Natalie Clarius 2022-06-14 15:28:18 UTC

Strangely it goes on and off; a couple days ago it was working again and I could also find the DBus command for it, then it broke once more and the DBus command was no longer to be found, and today it's working fine again. I have no idea what this might depend on. IIRC I didn't even reboot between one of the times it changed. 

During the times it is broken, I also noticed that the thumbnail grid in the Alt+Tab task switcher would only show application icons instead of previews. Someone else is having the same issue with the previews in the thumbnails in the task bar: https://www.reddit.com/r/kde/comments/vb54sq/hello_what_setting_do_i_need_to_change_if_i_want/ Could this be related?

Comment 3 Natalie Clarius 2022-06-29 02:46:27 UTC

It appears the DBus services become unavailable when compositing is disabled after KWin crashed; reenabling the compostior also makes the effects work again..

Comment 4 Natalie Clarius 2022-06-29 02:49:12 UTC

So I think this issue can be closed as not an actual bug, since it only happens when compositing is disabled which obviously can't work.