[Qt-interest] Catching focus events from child widgets

[Robert Hairgrove]

Is it necessary to subclass a child widget in a dialog and override the 
different focus events, for example, just so the parent knows when a 
line edit or spin box loses focus?  I couldn't find any way for the 
parent widget to get notification messages in such cases without doing 
it that way.

Seems like a lot of work; maybe there is an easier way?