GtkToolbar::insert_widget
void insert_widget(GtkWidget widget, string tooltip_text, string tooltip_private_text, int position);
Inserts a widget at the given position. The
position minimum value is 0, and the maximum is the number of items
on this toolbar.
The tooltip_text is the one being visible when
the mouse hovers over the element. The tooltip_private_text
is for context-sensitive help about this widget.