Safari 3.1 Gmail problem
If you upgraded your Safari to the new 3.1 version, use Gmail, and now your Shift or Tab keys are making your cursor jumping back to the To: field, here is the solution: change your default language to English (US); click on "Newer version" on the top right of the screen - only English (US) version has this option enabled; you are done, Gmail should be working perfectly now.
I guess people at Cupertino doesn't use Gmail...
Update: the same problem happens with Gmail for Google Apps, and I don't know how to solve it. Need a hand.