Tree view : expander clicked?

[Jérôme Couderc <j couderc ifrance com>]

Hi,

   When selecting a line of a tree view, I manage the "changed" signal 
with a function like : gboolean Node_Selected (GtkTreeSelection 
*selection, gpointer user_data)

In this function, I wanted to know if (when the changed signal was 
emitted) I've clicked over the expander to open the tree.

Note that when clicking over the expander, the selection doesn't change...

So how can I know if I've clicked the expander in the tree view to 
manage it in my Node_Selected function?

Thanks in advance,
Jerome