gtk/text_view.go
func (v *TextView) SetRightMargin(margin int) {
	C.gtk_text_view_set_right_margin(v.native(), C.gint(margin))
}
func (v *TextView) SetRightMargin(margin int) {
	C.gtk_text_view_set_right_margin(v.native(), C.gint(margin))
}
// SetRightMargin is a wrapper around gtk_text_view_set_right_margin().