Selection flickers to dark grey each time it moves instead of using the same light grey

[Daniel van Vugt]

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)

[Daniel van Vugt (vanvugt)]

The same dark grey is used on selections when the mouse button is held down. But this bug is not about a button being held down.

[Carlo Lobrano (c-lobrano)]

Hi Daniel,

could you take a video about this? I don't see any visible flickering hovering on gnome-shell menu, but maybe I misunderstood how to reproduce it.

[Daniel van Vugt (vanvugt)]

Yes I definitely will. This bug is frankly one of my personal top priorities and I too need to see a fresh slow-mo video of it to better understand what's happening.

[Daniel van Vugt (vanvugt)]

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

[Daniel van Vugt (vanvugt)]

That said, if you could quickly fade in menu selections instead of changing them instantaneously then that should be a workaround. It might also look nice for everyone else.