How to access gtktreeview header widgets ?

["Miroslav Rajcic" <rajcic sokrates hr>]

I am having treeview with visible headers.
What I need to do is to remove GTK_CAN_FOCUS flag from the header button
widgets
(GTK_WIDGET_UNSET_FLAGS(view, GTK_CAN_FOCUS)) .

My problem is that I don't know how to access header widget(s).
Is this possible ?

TIA,
  Miroslav Rajcic