The first time I saw it, I thought it was a UI bug. Is it supposed to expand, cartoonishly, beyond the confines of the existing bar, when you select it for input? It feels like an element designed as a helper for people with limited wrist/hand mobility (who need a larger target area) or poor eyesight.

I guess I'll head back to SeaMonkey now. The UI hasn't changed in a decade but at least the UI hasn't changed in a decade.