1)	The compound image stuff doesn't work.  CmpImg core dumps.
	This seems to be something to do with Tcl/Tkinter

	**** FIXED **** as of Tcl7.6, Tk4.2, Tix4.0.5

2)	tk.call is used a lot in the demos. These functions should be
	encapsulated somewhere in Python (more mods to Tkinter ?)

3)	Callback definition is not straightforward. A lot of the time
	a lambda definition has to be written. However, this is a
	general Tkinter problem.

4)	In the Control widget, the callbacks for increment, decrement
	and validate should return a string to Tix. Find a way to do
	this.