gtk/widget_since_3_8.go
func (v *Widget) SetOpacity(opacity float64) {
	C.gtk_widget_set_opacity(v.native(), C.double(opacity))
}
func (v *Widget) SetOpacity(opacity float64) {
	C.gtk_widget_set_opacity(v.native(), C.double(opacity))
}
func ( v * Widget ) SetOpacity ( opacity float64 ) { C . gtk_widget_set_opacity ( v . native ( ) , C . double ( opacity ) ) }
// SetOpacity is a wrapper around gtk_widget_set_opacity()
SetOpacity is a wrapper around gtk_widget_set_opacity ()