[gnome-love] Correct way to create a child window?

[captain deadly gmail com]

Hello all,
    I'm just starting out on writing gnome apps and wondering is there a 
correct way to create a child window from a parent and display it. process 
input from the child and then when it's finished drop back to the parent. 

I'm searching the web but can't find anything specific, but that maybe down to 
my search string. There are probably a few ways. I could reuse my current 
toplevel window remove everything out of it and re populate it with the GUI 
Elements which my child needs. Then when the child terminates repopulate 
again. Or I could create a brand new top level windwo and populate it leaving 
the previous window in place. 

This is a very basic question I know and maybe there ain't even a right answer 
to it. In any case if anybody can offer any advice I'd be very gratefull.