[Gtk-sharp-list] Accessing data from one window by another

[Ryan]

I don't know if the subject is quite but here goes

If I have Window1 open then the user wants to do something in WizardWindow.
When the user finishes enter the data and clicks ok how can I get the 
TreeView widget
in Window1 to refresh (either appending or deleting the item)

At the moment I'm passing the entire instance of Window1 to WizardWindow.
This way I can get the Treeview to update when adding an item but not 
removing an item.

I'm sure there's an easier or better way out there but I'm running out 
of places to look. And I'm really not quite sure what I'm look for.

If someone can point me in the right direction it would be appreciated.

RT