weird delete-forward when current word is succeeded by a tab on FF

[feedthejim]

Steps to repro:

• insert Foo\tabbar
• Move cursor at the start of Foo
• delete forward
• notice the tab just got expanded

Screen.Recording.2021-02-10.at.15.47.33.mov

[steveluscher]

It's not so much that the tab expanded, as it is that the tab was not deleted. It appears to have grown because that's where the tab stop is and the word ‘Hello’ is no longer in its way.

This is just how deletion works in Firefox; try it with a raw HTML <input>: https://jsfiddle.net/12aj3Ln7/

[steveluscher]

Feel free to reopen this, @feedthejim, if I missed something!