Good news for everyone but me! This is a feature/imperfection in the design of my Dell U2413 monitors. The "bug" does not occur on any other screen that I can find.
The problem I am seeing on the Dell U2413s is called LCD Response Time Compensation (RTC) or just "overdrive". It is a technique used to avoid ghosting but means the LCD very briefly switches to the wrong colour level as shown in the attached measurement from an actual Dell U2413. Article about my problematic monitors: https://www.tftcentral.co.uk/reviews/dell_u2413.htm#gaming A handy web site for testing the various modes of your monitor: https://www.testufo.com/eyetracking ** Attachment added: "50-255.png" https://bugs.launchpad.net/ubuntu/+source/yaru-theme/+bug/1846447/+attachment/5311278/+files/50-255.png ** Changed in: ubuntu-ux Status: New => Invalid ** Changed in: yaru-theme (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to yaru-theme in Ubuntu. https://bugs.launchpad.net/bugs/1846447 Title: Selection flickers to dark grey each time it moves instead of using the same light grey Status in Ubuntu UX: Invalid Status in yaru-theme package in Ubuntu: Invalid Bug description: Selection flickers to dark grey each time it moves instead of using the same light grey. You can see this (only just) when moving the mouse over the gnome-shell calendar, or in the system menu. This makes the GUI feel more stuttery than it really is. And once you finally see the problem it cannot be unseen. I think this is a historical design choice given that the same issue was visible in Unity back in to 2016 (bug 1545945). Affects: yaru-theme-gnome-shell and yaru-theme-gtk ProblemType: Bug DistroRelease: Ubuntu 19.10 Package: yaru-theme-gnome-shell 19.10.4 ProcVersionSignature: Ubuntu 5.3.0-13.14-generic 5.3.0 Uname: Linux 5.3.0-13-generic x86_64 ApportVersion: 2.20.11-0ubuntu7 Architecture: amd64 Date: Thu Oct 3 13:53:20 2019 Dependencies: InstallationDate: Installed on 2019-05-02 (154 days ago) InstallationMedia: Ubuntu 19.10 "Eoan EANIMAL" - Alpha amd64 (20190501) PackageArchitecture: all SourcePackage: yaru-theme UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-ux/+bug/1846447/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
