The "Backspace" key works fine, but pressing "Delete" adds "DEL" (with a box around it) to the search field. Given that there's no caret/cursor, pressing "Delete" should have no effect at all. So, knowing this, why the hell did I press it? I don't know the answer to that question. Either I had a momentary lapse of reason or I was subconsciously doing some bug testing for you :-). Reproducible: Always
*** This bug has been marked as a duplicate of bug 352416 ***