I’ve found myself continually frustrated with the behavior of Tab in OS X when filling out forms on web pages. I fill out my name, press tab, fill out something else, and then press tab to select a checkbox but OS X by default won’t let you tab into a checkbox.
I decided I had enough of this and did a little research. I’m happy to report this can be fixed! Go to System Preferences and select your Keyboard & Mouse settings. Switch to the last tab, Keyboard Shortcuts. On the bottom you can switch tab behavior to honor All Controls. Yeah!