Upgraded to 5.28.1: control-b doesn't do what i expect

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Summary

Pressing control-b inserts asterisks to bold whatever I’ll type next instead of moving the cursor back one character.

Steps to reproduce

Press control-b in the text-input pane. Server 5.28.1 (team), MacOS desktop client 4.6.1, tested with the web interface as well.

Expected behavior

As a long-time emacs user, I expect it to move the cursor back one character as it did in earlier versions of Mattermost.

Observed behavior

It inserts **** and positions my cursor between the two pairs of double-asterisks.

Other electron apps do not do this. C-{a,e,f} work properly. This is a major usability issue for me.

This was implemented here: https://github.com/mattermost/mattermost-webapp/pull/6230.

I’m not able to reproduce moving the cursor back one character in a previous version. What server version did you upgrade from?

I upgraded the server from 5.27.0, which I installed on September 20. I don’t remember which version of the desktop client I had before I upgraded to 4.6.1 yesterday.