At certain screen resolutions, the text box view itself seems to move left and right internally. To reset it, you need to go all the way to the left. It is especially annoying because this incorrect behaviour is default on the standard text width in new Vector. If this could be fixed, it would go a great way toward usability.
Topic on Talk:2017 wikitext editor
Are you still having this problem? (I know that one bug was fixed already.)
I am still having this issue. The issue only occurs when making the width of the window something that isn't a full integer multiple of the monospaced text. In such a case, the internal screen moves to show the remainder by moving to the right.
I'm still getting this issue; for some reason it seems that the internal screen moves when the cursor is near the end of the line rather than when it actually gets beyond the end of the line. I don't know why that is the case.
Regardless, it is annoying because it screws up the carat display and makes text selection inaccurate.
I've not been able to reproduce this. Is there any chance that you could make a short screencast and e-mail it to me? I'll send you a quick e-mail message now that you could reply to.
I've started a bug report at phab:T334994 (you're welcome to edit it; just log in to your regular wiki account), but I don't know if Phabricator accepts videos.
I'm currently at work but I can reproduce the error on my iPad browser too. Uploaded as an unlisted video at https://youtu.be/kUvwP7RsxFs.
I can also reproduce after commenting out everything in my commons.js file.
That looks terrible. I'll ping the devs.
I can't log in to Phabricator and don't receive any emails that it alleges to send. I saw that someone can't reproduce. I have no ability not to reproduce on English Wikipedia; I've disabled every gadget but default, disabled everything in common.js, changed themes (back to Vector 2010 and it still has this issue). I've switched computers from iPad to macOS to Windows.
It's even worse on Firefox, where it double-displays text like this: https://imgur.com/DqLCI4z.
Okay, I disabled the beta feature for discussions after comparing my main account's settings with a puppet account's settings; it seems there is some kind of incompatibility with the Discussion tools beta feature?
Actually I can still reproduce even with Discussion tools disabled. It seems, however, to trigger with much lower sensitivity?
Okay, Ifly6 here on a clean account for testing; I am unable to reproduce in the editor if syntax highlighting is off but it does reproduce if syntax highlighting is enabled.
@DLynch (WMF) is one of the devs on the Editing team.
Does turning off syntax highlighting solve the problem in your regular account? Safemode might be an easier way to test some of this, but you sound like a technically capable person, so do you know how to check for errors in your browser's web console? (No problem if you don't – I ask the devs every time they want me to do this. ;-) )
Turning off syntax highlighting does solve the issue in my normal account; though given how useful syntax highlighting is, this is not really a solution. I tested with safe mode and am able to reproduce the movement when syntax highlighting is turned on. I opened the developer console and saw no errors.
Also, as I checked the ticket in Phabricator, thanks for moving it up the chain and identifying (possibly) the relevant library.
@Ifly6, @MusikAnimal (WMF) wondered whether this problem appeared for you in the 2010 wikitext editor (the most common one in Wikipedias). If it doesn't, he's got an idea about a temporary fix. The (possible) real fix might happen later this year.