This signal is emitted when the user unselects a row in the list.
It is emitted for every row that is unselected in a multi-selection or by calling
unselect_all.
It is also emitted for the previously selected row in a "single" or "browse"
mode GtkCList.
Callback function
void callback(GtkCListwidget, int row, int column, GdkEventevent);
