Well, are the "tabs" just buttons in another frame? then do something in their onclick, to check on the status of the form in the current/previous frame, ... have a bunch of status indicator variables, 1 or 2 for each form+frame. Have each form set its status indicator variable (declared either in its own frame, or in the parent?) to indicate that the user is beginning to fill it out. Then have it set an indicator to indicate it is done (how do you tell?). Meanwhile in the onclick of the tab button, check these indicator variables, to tell if any form, in any frame, has been started but not completed?

Also about "saving changes", how do you save the state and later "restore" those changes, to a partially completed form?