newbie: How do I place cursor(set focus) in specific gtkentry?

[David Capps <cncprgr aim com>]

I am putting together a simple app (using Python 2.4, 
gtk-win32-2.8.6-rc2, Glade 2.12.1, GladeGen) that does some 
calculations. It has three entry boxes, some labels and a couple of 
buttons. When one button is clicked it clears the entry boxes and leaves 
the clicked button with focus. I want to have the cursor move to the 
first entry box so I can begin typing immediately, without having to 
click in the first entry with mouse. How do I do this? Nothing I have 
found in documentation or tried on my own has worked.
dc