Using a TreeStore with a ComboBox

[Jef Driesen <jefdriesen hotmail com>]

Using a treestore model with a combobox creates a nice dropdown list 
with submenus. Inside each submenu, the parent item is shown with a 
separator below to separate it from its children. I want to know how I 
can hide this parent node, so I can only select leaf nodes (e.g items 
without children).

The model contains places that can be are arranged by the user in an 
arbitrary hierarchy, to group related places together (for instance by 
continent and/or country). This is very similar how files (my places) 
can be arranged into directories (my hierarchy). But when the user needs 
to select a place with the combobox, it doesn't make sense to be able to 
select an item that is not a place.