As there are two types of model - TreeStore and ListStore and only one type of view - TreeView, it is not obvious how to share a model between two views.

The trick is to use one model and one view but to control the visibility of row expanders. All we have to do is to add a first dummy column (with no model column equivalent), keep it hidden all the time and switch the 'expander-column' property between this and next column (having 'expander-column' set to column that is not visible effectively hides the expanders).

Please note the user has no way how to expand/collapse the rows when the expanders are hidden - it is useful to expand all rows prior to hiding the expanders.

hide the dummy column:

  treeview.get_column(0).set_property('visible', False)

hide the expanders:

  treeview.expand_all()
  treeview.set_property('expander-column', self.treeview.get_column(0))

show the expanders:

  treeview.set_property('expander-column', self.treeview.get_column(1))

See also en.wikibooks.org/wiki/GTK+_By_Example/Tree_View/Miscellaneous