I thought I blogged this earlier, because I have had problems with this every time I reinstall Mac OS X, or buy a new Mac.
In Firefox, there is a problem tabbing, especially through form fields in Mac OS X.
It is a very easy fix. In System Preferences>Keyboard & Mouse Preferences>Keyboard Shortcuts. Choose the the setting “All Controls”

Can’t get any easier than that! And now you will have much better tabbing control when using Firefox in Mac OS X.
Make sure you restart firefox. If you afraid of losing all the opened tabs than better to download: https://addons.mozilla.org/en-US/firefox/addon/1249
Comment by Aamir on May 29th, 2008Thank you so much for this post! I am still learning the ins and outs of the mac interface after 10 years of Windows.
Comment by mac switcher on July 9th, 2008