Tabbed group background thingies

[Andy Calloway]

Having read a bit of Dan's book and gone through a couple of the RunRev
demos, I thought I'd try to apply what I'd just learned so I went back to a
stack with tabs on it. It's got three tabs and I've added some text fields,
buttons etc to some of them. It worked fine, click on a tab and the new
objects leap into view.
 
Then I got too cocky and added another tab between the first and second one.
Now, when I click on it, the items from the previous selected tab remain in
place where I would really expect it to be blank.
 
Have I missed something here?
 
Andy.