treeview widget sizing

[Carl Nygard <cjnygard fast net>]

I'm using glade, and trying to get my treeview widgets to size smaller. 
The default seems to be rather large buttons and row sizes (at least
vertically, there seems to be unnecessary white space).

I'd like the treeview to size like Evolution does, where the buttons and
rows are thinner vertically.

So.... how?  Can someone point me to code in evolution, or some other
keyword for googling?