[Bug 1961750] Re: ubuntu mate focal.4 adjusting display config causes part of screen to become unusable

[Expired for linux (Ubuntu) because there has been no activity for 60
days.]

** Changed in: linux (Ubuntu)
Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/1961750

Title:
ubuntu mate focal.4 adjusting display config causes part of screen to
become unusable

Status in linux package in Ubuntu:
Expired
Status in ubuntu-mate-meta package in Ubuntu:
Invalid

Bug description:
Ubuntu-MATE 20.04.4 RC live test on
- dell [optiplex] 780 (c2q-q9400, 8gb, amd/ati cedar radeon hd 5000/6000/7350/8350)

My displays don't match default setup. To have it match my setup I
need to

- swap left-right
- my left is landscape (no change needed here)
- my-right is portrait-left

** Expected

On perform the steps above; I expect both screens to be usable
performing prior steps

** Actual

The lower section of the now portrait-left display is now a changing
image, as I type this it's changing; though if I stop typing it's
changing as the cursor on the firefox window blinks too (ie. very
regular pattern).

What's in that lower section of the display appears to be made up from
elsewhere on the screen.

See attached pictures

Please Note: I'm sure this is a duplicate report; but I didn't find
it (for tagging of LIVE QA-test of focal.4 RC) thus this filing..
If/when I find it I'll mark it duplicate.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubuntu-mate-core 1.263
ProcVersionSignature: Ubuntu 5.13.0-30.33~20.04.1-generic 5.13.19
Uname: Linux 5.13.0-30-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.445.1
CurrentDesktop: MATE
Date: Tue Feb 22 08:42:08 2022
LiveMediaBuild: Ubuntu-MATE 20.04.4 LTS "Focal Fossa" - Release amd64 (20220221)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-mate-meta
UpgradeStatus: No upgrade log present (probably fresh install)

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