Enabling tabbing to select boxes in Firefox 3.5 on the Mac

After upgrading to Firefox 3.5, I could no longer use the TAB key to move to select boxes on my Mac.  I found the solution on the Mozillazine Forums:

1. Go to "about:config"
2. Right click to manually create an "accessibility.tabfocus" entry as an integer
3. Set the value to 3

Worked for me.