I just noticed that if I hit the down key right before typing the second character in FF, it will work correctly. Now I just have to figure out how to simulate hitting the down arrow key.
As for using the input. I’m not sure. I think that would lead to flashing since the input event would run AFTER the text is in the box. The other big benefit of using beforeinput is that its data property will be null if a non-character key was pressed, which helps with a lot of things.
EDIT: I got it, problem solved