Bug 398438

Summary:	Desktop cube corruption on misaligned multiple monitors
Product:	[Plasma] kwin	Reporter:	Mayeul C. <oss+kde+bugzilla>
Component:	effects-various	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED DUPLICATE
Severity:	normal
Priority:	NOR
Version:	5.13.5
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:
Attachments:	Original layout Screenshot of the problem

Description Mayeul C. 2018-09-09 19:59:01 UTC

Created attachment 114866 [details]
Original layout

I have three monitors, which are not aligned in a straight way, to match the physical layout. The resulting layout can be seen in the first attachment.

When using the desktop cube animation to switch virtual desktops, corruption is shown on my screen.

This bug dates back to the kde4 days, as far as I know (it might have been fixed at some point, though).

I am using an Intel igpu on this specific computer, with Mesa 18.1.8.

Top-left, with the shape of an auto-hiding panel (see bug 382829) that sits here, appears a part of another activity. I do not see that myself (just the panels that becomes semi-transparent; with the right background) when switching desktops, it only appears on the screenshot.

Screenshots taken with spectacle

Comment 1 Mayeul C. 2018-09-09 20:00:30 UTC

Created attachment 114867 [details]
Screenshot of the problem

Comment 2 Vlad Zahorodnii 2018-09-09 20:13:49 UTC

(a) can you reproduce this issue when all screens are aligned in a straight line?
(b) can you reproduce this bug if you disable the blur effect (and the background contrast effect)?

Comment 3 Mayeul C. 2018-09-10 08:41:27 UTC

> (a) can you reproduce this issue when all screens are aligned in a straight line?
> (b) can you reproduce this bug if you disable the blur effect (and the background contrast effect)?

Short version:
(a) Yes.
(b) Yes with blur, no with background contrast.

Longer version:

(a) It seems to happen only if the two following conditions are met:
* The two screens on the left share the same Y-coordinates
* The screen on the right is lower than this.

It doesn't happen if either:
* One screen is disabled
* The screen on the right is above
* The two left screens are misaligned

(b) The problem seems fixed now without background contrast. Furthermore, it didn't reappear after re-enabling it.
Both blur and background contrast were originally only partially checked. I have no idea what this means. They are both fully checked now, and it seems to be working. This survived across a session connect-and disconnect.

That means I can't reproduce the bug anymore for now. I'll write back if it happens again.
Thanks for your help :)

Comment 4 Vlad Zahorodnii 2018-09-10 08:50:30 UTC

(In reply to Mayeul Cantan from comment #3)
> (b) The problem seems fixed now without background contrast.
You mean the blur effect, right?

Comment 5 Mayeul C. 2018-09-10 12:33:04 UTC

(In reply to Vlad Zagorodniy from comment #4)
> (In reply to Mayeul Cantan from comment #3)
> > (b) The problem seems fixed now without background contrast.
> You mean the blur effect, right?

No. I was able to reproduce this bug with with the blur effect disabled. Then I am pretty sure I re-enabled it.

I have not been able to reproduce it after disabling the background contrast effect, either with or without the blur effect.

As a matter of fact, I have not been able to reproduce this bug ever since I switched the background contrast effect off, then on again.

Comment 6 Vlad Zahorodnii 2018-09-10 19:45:00 UTC

Thank you for the info.

*** This bug has been marked as a duplicate of bug 362360 ***