It’s kind of annoyed me for a while, but the default behavior of tabbing through controls on a web form in a browser (let’s say FireFox) on a Mac will completely skip drop-down boxes. The drop-down or select boxes are an integral part of every form I’ve ever made on the web, so the fact that you can’t use the keyboard to navigate to them was very troubling to me. I have since found a setting that will change that behavior. The problem was not with FireFox, but with a setting on the Mac. Just open System Preferences and change your setting to the following: