I'm using an NSComboBox to autocomplete a username that one of our user interfaces accepts. When a login is successful, the username is added to the combo box the next time a login is needed.
I'd like to implement deleting items out of the list in the combo box. My initial idea was to wait for a reverse-backspace key press that otherwise does nothing (cursor on the right side of the text and nothing highlighted; the delete key does nothing); while the combo box is expanded and has a selection, delete that row.
However, I'm having trouble capturing a key down event. I tried guessing the elements in the responder chain, choosing an object, subclassing, and adding a key down handler. However, my guesses of what's in the responder chain (the combo box and the window) were either not correct, or something above those objects consumed the key presses and did not forward the event along the responder chain (which, come to think of it, would actually be the expected behavior if NSComboBox uses a different view to manage the editable field).
Any ideas on how I can make this work? I like my initial idea, because it feels like a clean interface; but I can think of some other clean ways to do it, too.