Sizing gtk windows to smaller sizes from within a program?

[dath sequent com]

	A little while back I asked a question about how to set the size of a window 
from within a program.  At the time I was using the following call to set the 
size of the window (something which happens frequently in my program):

  gtk_widget_set_usize(win, w, h);

	This worked great to make the window larger, but the window would never 
shrink...  So after I posted this to the list someone (I can't remember who 
for sure) told me that I could use the following instead:

  gtk_window_set_default_size(GTK_WINDOW(win), w, h);

	This doesn't seem the affect the size of the window at all?  I don't know 
what I'm doing wrong.  I know that gdk has a simple function just to set the 
size of a window gdk_window_resize(), which with gdk works quite nicely to 
resize the window to any arbitrary size.  I am trying to figure out what I 
need to do in gtk to accomplish the same thing?  Is there something I just 
don't know about the gtk_window_set_default_size() function?

	Thanks Much,
	-dath