I’ve become more and more convinced, that whatever the question, drop-down select boxes is never the answer. If it’s a large list it should be an combobox/livesearch box (select box alternate OK for accessibility), and, for what is more often the case, if it’s a small number of options, it should just be listed, or otherwise expandoed. No muss, no fuss, no crazy key selection, z-index and styling problems, and a more humane user experience overall.