code: func (v *TreeView) GetExpanderColumn() *TreeViewColumn {
  	c := C.gtk_tree_view_get_expander_column(v.native())
  	if c == nil {
  		return nil
  	}
  	return wrapTreeViewColumn(glib.Take(unsafe.Pointer(c)))
  }
docs: // GetExpanderColumn is a wrapper around gtk_tree_view_get_expander_column().