[Urwid] detecting when an edit box has changed

[Eric S. Johansson]

Ian Ward wrote:
> With Urwid 0.9.5 you can now hook the set_edit_text() function to 
> capture all changes to the text in an Edit widget.

this does help but I'm going to say something that really displays my 
ignorance.

What do you mean by hooking a function in Python?  I'm familiar with 
lots of techniques using pointers to functions in a variety of different 
languages.  so is there a function I overload or pass into the constructor?

I've even done a simple google but I'm coming up blonde.