preserving row expansion/collapsing

["Calin Vatavu" <cvatavu bumerang ro>]

Back in gtk-1.2 the preserving of row expansion/collapsing state was a 
feature in GtkCTree widget. But now, in GtkTreeView, when a row is collapsed 
and expanded again it's children are all collapsed no matter how they were 
before. 

Probably there's an option in GtkTreeView which modifies this behaviour? 

Thanx