Bug 389215

Did you try with another desktop theme, preferably Breeze? Do you have compositing on or off?

Got another report of this issue: https://pointieststick.wordpress.com/2018/01/20/this-week-in-usability-and-productivity-part-2/comment-page-1/#comment-167

The reporter originally had a single pixel in the corner from the desktop, but after moving the panel, now has the same issue outlined here--there's a line of pixels from the desktop on the bottom of his panel. He can reproduce the issue using KWin or OpenBox as the WM and is using the standard Breeze theme.

Created attachment 110061 [details]
Another occurrence of the issue

Created attachment 110062 [details]
Corners of the taskbar

The attachment 110061 [details] is actually my taskbar. If I try to move it from the bottom to a side, and then back, this gap happens. And only killing and restarting plasmashell solves the issue.

But without any action from me, the corners of the taskbar seems a little bit rounded, as you can see in attachment 110062 [details]. And that is the bottom left of my screen, so at that pixel, the launcher isn't accessible.

(In reply to Kai Uwe Broulik from comment #1)
> Did you try with another desktop theme, preferably Breeze? Do you have
> compositing on or off?

Sorry but i'm not able again to reproduce the issue, but as other said it's not caused by those.
I have no idea of how i fixed, but maybe this issue is random.
PS
when i was having this problems, a reboot didn't fix.

I'm experiencing this bug again, if someone need to test anything or get a log please ask me

Can you *move* but don't delete:

~/.cache/plasma_theme_default_v5.30.kcache

if that fixes it, can you upload your old version.

Your v5.N numbers might be different, also a different name if you use a different theme.

I have cut to another directory, now i have to logoff/restart to try if that fixes?

(In reply to mac12 from comment #9)
> I have cut to another directory, now i have to logoff/restart to try if that
> fixes?

Ok file was automatically recreated, but issue is not fixed, i have to reboot?

yes.

or from a console

kquitapp5 plasmashell
plasmashell

(In reply to David Edmundson from comment #11)
> yes.
> 
> or from a console
> 
> kquitapp5 plasmashell
> plasmashell

Tried with kquitapp5, bug still there, now i try rebooting but i don't think will help

I probably phrased that badly.

Can you quit plasma
move the file
start plasma


if it saves what it had in ram, then we're not testing anything.

(In reply to David Edmundson from comment #13)
> I probably phrased that badly.
> 
> Can you quit plasma
> move the file
> start plasma
> 
> 
> if it saves what it had in ram, then we're not testing anything.

Sorry, i didn't uderstand.
I've quitted using kquitapp5 plasmashell, cut the file to another directory and then restarted, but still there.

Oh ok, then it's not the issue I expected..

Just for info, I destroyed my home partition today, so I had a new home folder created from scratch, and this bug was present. The screenshot I shared was in Breeze dark, and with a fresh home, it was Breeze light. In both case the issue was present.

I've found the source of bug: OpenGL 3.1
After setting 2.0 as default compositor issue was fixed.
(and after re-setting it to 3.1 issue wasn't here, so probably its random)

Created attachment 110415 [details]
set Opengl 2.0 to fix the issue

yeah, we've only seen this when the panel is in non-composited mode

(In reply to David Edmundson from comment #19)
> yeah, we've only seen this when the panel is in non-composited mode

And in fact opengl 2.0 is the default as i remember, so this is why this issue is not widespread.

Hoewer, now i can't test anything because i have fixed, i will wait until i get it again.
Prepare a list of things to try :D

Got another report of this: https://www.reddit.com/r/kde/comments/7xxtqd/why_does_my_panel_suddenly_have_a_wierd_gap/

>Got another report of this
Please don't do that.

If the user wants to get it fixed, send him here. I don't go the other way.

To expand on what I'm 90% sure the problem is.

We have a different FrameSVG used for when we have compositing or not.
The glitches have only been reported (I think) since the big FrameSVG refactor.

Something gets glitchy only with the opaque versions, and only here in the panel.
Normally a cache clear seems to fix it (though apparently not for OP) 

--

if anyone has this please send:

output of xprop (then clicking on panel)
their ~/.cache/plasma-svgelements-whateverIsRelevant

Created attachment 110726 [details]
output of xprop

Created attachment 110727 [details]
add ~/.cache/plasma-svgelements-breeze-dark_v5.30

As asked, I added my xprop output and the svgelements. I'm available to upload any files you need.

*** Bug 390662 has been marked as a duplicate of this bug. ***

FWIW, in Plasma 5.12.3, I can now reproduce this 100% on demand simply by turning off compositing. So that supports your theory, David.

Created attachment 112294 [details]
still present on 5.12.4

Now i have this issue at every reboot, to fix i have simply to set opengl 2.0, after the issue is fixed until next reboot.

fixed by https://phabricator.kde.org/R242:412a517576d5505c9f700f13b8f33257c07e220d

plasmashell 5.17.2 sitll have this issue.
seting OpenGL as the compositor fix the issue.
To make this work without compositor, I've edited `/usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Panel.qml` and commented line 33 (`property alias panelMask: root.mask`)

If you're still having the issue, please re-open the bug. :)

Can you submit a patch on Phabricator, if even just for discussion purposes? See https://community.kde.org/Infrastructure/Phabricator for instructions.

Thanks for your reply,
I only get this issue when using the 'Arc Dark' Global theme.
With the 'Breeze' theme I don't get this issue.

I'll first report to the 'Arc Dark' team. 
xRef: https://github.com/PapirusDevelopmentTeam/arc-kde/issues/76

Seems like this is a theme-specific issue.