Close nodes in Tree View widget

[andrew at midwestcoastmedia.com]

I'm working with the Tree View widget and have found that leaf nodes  
stay open even after the arrayData has changed. For example, if I  
click on leaf node 2 and 4 to open them up for further inspection but  
then load new arrayData those same leaf nodes are already expanded  
with the new data.

Is there a way via code to close all the leaf nodes, or to restrict  
the widget so only 1 node can be open at a time?

--Andrew Bell