This is either one of two things happening:

- Something weird about Zope
- Something weird about the tab handling code I ripped off from XUF (if you look
at XUF, the same thing happens).  

I think it might actually be the former, most of the ZMI based stuff in terms of
the tabs is handled automagically

I never really noticed that happening though.  In the client end I explicitly
check which tab is active but the ZMI does its own thing I believe.