Cursor jumping around in composer / editor text box

Contribute Bug
21

I am not shure if this is a regression, but I re-open this topic again:

In the current composer window (the new one based on https://prosemirror.net/), I also see these “jumping effects”: the editing window moves to the top of the text and you have to re-position your cursor again.The re-formatting of longer text parts sometimes is nearly impossible (e.g. a clean up when migrating from other platforms to Discourse and cleaning up the content).

Here is a short screencast where the jump is visible close to the end. Its a bit hard to describe it, but its really annoying especially if you are working on larger posts.

Environment: Discourse 2026.4.0-latest, Firefox 149.0.2 (also visible with previous FF versions and other browsers)

22

This seems like a different problem, especially because it’s on desktop, and the video doesn’t show the new composer based on ProseMirror. It’s toggled to the Markdown mode – the mode that shows the rendered preview on the right side.

Can you reproduce this behavior in more than one Discourse instance (e.g., here or on try.discourse.org)?