I forgot something in the instructions for typing Arabic:
While typing in the Arabic, you also have to switch the LyX-language to Arabic. This can either be done with a key binding, as Dekel's instructions show; or by just typing "language arabic" in the minibuffer (although for some reason I find that with the latter, I can only apply this to some already typed text --- trying to set the language that way before starting to type doesn't seem to work through the minibuffer. I suspect this is some focus issue or something...)
