GtkComboBox question

[Igor Korot <ikorot earthlink net>]

Hi, ALL,
I am looking at this page: http://library.gnome.org/devel/gtk/stable/GtkComboBox.html.

There is a "popup-shown" property that reads:

"
Whether the combo boxes dropdown is popped up. Note that this property is mainly useful,
because it allows you to connect to notify::popup-shown.

Default value: FALSE

Since 2.10
"
However I can't find the documentation about "notify::popup-shown" signal/event.

Basically I'm looking for a way to override the mouse click on the arrow for
the combo box when the list either pops-up or closes down. If this is not the
right event/signal, please let me know.

Thank you.