How to link expand/compact behavior of two treeviews?

[Steve Madsen <smadsen dnahelix com>]

Hi all,

I found the thread "Freeze a treeview column" from April 2004 very
useful, and am using two treeviews which share a model for a project.
The linking of the scrollbars was easy, but I also need to link the
expand/compact behavior of the two views (so when the user clicks
the little triangle to expand the children in one view, the triangle
also gets "clicked" in the other treeview)

Any ideas on how to do this?  In the meantime I'm looking at
the documentation and searching the archives, but so far nothing...

Thank you

P.S.  The thread can be found in the Apr 2004 archives, here's a 
relevant post
       with working sample code in case you're interested:
   http://mail.gnome.org/archives/gtk-perl-list/2004-April/msg00113.html