gtk/icon_view.go
func (v *IconView) SetMargin(margin int) {
	C.gtk_icon_view_set_margin(v.native(), C.gint(margin))
}
func (v *IconView) SetMargin(margin int) {
	C.gtk_icon_view_set_margin(v.native(), C.gint(margin))
}
// SetMargin is a wrapper around gtk_icon_view_set_margin().