Tkinter MDI-style widget?

[Paul Miller]

I posted a couple of days ago looking for pointers on how to create a
wiget that has a settable title and can't be moved outside the parent
widget.  What I'm really looking for is a Windows-style MDI widget. 
Does this exist/is it possible to make in Tkinter?

The only thing I know of that behaves sort of the way I want is the
Tkinter canvas item.  Now I know you can create new canvas items
through the tcl C interface, but would even that make it possible to
do what I want?  (Not that I really want to go that route, anyway.)