When selecting or navigating text with CTRL + LEFT ARROW or RIGHT, or even just mouse clicking within text, the cursor jumps backwards and forwards erratically

[Adam Bishop]

This started happening recently. Perhaps after a kernel update. I'm now on Ubuntu 21.10, running kernel Linux 5.13.0-22-generic, on a Huawei Matebook Pro X (2020).

[Adam Bishop (adambishop-it)]

Xev correctly reports key presses.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

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[Adam Bishop (adambishop-it)]

This may be to do with fractional scaling in Xorg (not Wayland). I'm using fractional scaling at 150% - it has never been a problem until now. However, I will test to see if the problem appears at 100% or 200% scaling. It would be a shame if, because of this, I have to use 100 or 200% scaling, since 150% scaling is perfect for this HDPI screen.

[Adam Bishop (adambishop-it)]

With fractional scaling at 150%, it occurs only after some time. On a fresh reboot it isn't apparent, but it gradually gets worse when manipulating text. It's as if some error accumulates with time. After a while it becomes really annoying when working with text. The cursor position is correct, but often isn't where you see it. The cursor may appear at the end of a word while you are actually editing the beginning of the word.

[Adam Bishop (adambishop-it)]

Have been testing at 100% and 200% scaling - so far the problem hasn't appeared at these scalings, which makes me suspect it is a problem with fractional scaling. It's a new problem, as, about a month ago, there was no such problem with the same fractional scaling - I have always preferred 150% on this system.

[Adam Bishop (adambishop-it)]

On 100% scaling it is certainly less noticeable, though the cursor sometimes appears slightly moved to the right of where it actually is. The screen resolution I am using is (and always has been) 3000x2000. Maybe it has something to do with this less common screen ratio.

[Daniel van Vugt (vanvugt)]

Thanks for the bug report. Which apps are affected?

[Adam Bishop (adambishop-it)]

It seems to affect different apps. Certainly it affects Mozilla Firefox, Gnome Text Editor Gedit, a Java-based translation app I use called OmegaT, and Microsoft Office Word and Excel 2006 running under Wine32.

[Daniel van Vugt (vanvugt)]

I can't seem to reproduce the issue in those apps, on Xorg with fractional scaling. Although I am using 22.04.

Does the same happen in a Wayland session?

Does the same happen if you use a USB keyboard?

[Adam Bishop (adambishop-it)]

A few days ago an Xorg update came in. After this update, the problem hasn't presented itself again. Therefore, I think we can consider this bug now resolved. Many thanks to Daniel and Brian for taking a look at it.

[Adam Bishop (adambishop-it)]

The bug has returned unfortunately. Terribly annoying. Only restarting my computer seems to set it back to normal. Affects all text entry apps, including Terminal.

[Daniel van Vugt (vanvugt)]

Please answer the questions in comment #9.

[Launchpad Janitor (janitor)]

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