void set_column_span_column(int column_span);

column_span : A column in the model passed during construction.

The set_column_span_column() method sets the "column-span-column" property to the value specified by column_span. The "column-span-column" property indicates the column in the associated GtkTreeModel row that contains an integer that indicates how many columns the item should span.

See also: get_column_span_column()