Mouse cursor jaggy movements

[Wolf Rogner]

Ever since the update of libmpfr4:amd64 (3.1.6~rc1-1, 3.1.6-1) on 2017-09-08 12:28:20
the mouse cursor demonstrates a jumpy / jaggy behaviour.

Compared to a similar machine or the live cd the mouse seems to jump around.

Testing with a handwritten text in Gimp demonstrated the difference.

This might not be an Xorg error but rather a Wayland | Mutter | libmpfr issue (I really can't tell but had to make a start)

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: xorg 1:7.7+19ubuntu2
ProcVersionSignature: Ubuntu 4.12.0-13.14-generic 4.12.10
Uname: Linux 4.12.0-13-generic x86_64
ApportVersion: 2.20.7-0ubuntu1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Fri Sep 8 19:05:34 2017
DistUpgraded: Fresh install
DistroCodename: artful
DistroVariant: ubuntu
DkmsStatus:
 virtualbox, 5.1.26, 4.12.0-12-generic, x86_64: installed
 virtualbox, 5.1.26, 4.12.0-13-generic, x86_64: installed
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation Iris Graphics 6100 [8086:162b] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Apple Inc. Iris Graphics 6100 [106b:013f]
InstallationDate: Installed on 2017-09-05 (3 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Alpha amd64 (20170902)
MachineType: Apple Inc. MacBookPro12,1
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.12.0-13-generic.efi.signed root=/dev/mapper/ubuntu--vg-root ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/18/2017
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP121.88Z.0167.B33.1706181928
dmi.board.name: Mac-E43C1C25D4880AD6
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro12,1
dmi.chassis.type: 9
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-E43C1C25D4880AD6
dmi.modalias: dmi:bvnAppleInc.:bvrMBP121.88Z.0167.B33.1706181928:bd06/18/2017:svnAppleInc.:pnMacBookPro12,1:pvr1.0:rvnAppleInc.:rnMac-E43C1C25D4880AD6:rvrMacBookPro12,1:cvnAppleInc.:ct9:cvrMac-E43C1C25D4880AD6:
dmi.product.family: MacBook Pro
dmi.product.name: MacBookPro12,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.82-1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.2.0-0ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 17.2.0-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.3-1ubuntu6
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.9.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20170309-0ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2

[Wolf Rogner (war-rsb)]

Played around with magnification.
Pressing Super-Alt-8 somehow creates this situation.

Increasing the magnification to 200%, pressing Super-Alt-8 and reverting to 100% remedies the effect.

Thus: An issue that I cannot explain.