code: func (t *Tooltip) SetIconFromIconName(iconName string, size IconSize) {
  	cstr := C.CString(iconName)
  	defer C.free(unsafe.Pointer(cstr))
  	C.gtk_tooltip_set_icon_from_icon_name(t.native(),
  		(*C.gchar)(cstr),
  		C.GtkIconSize(size))
  }
docs: // SetIconFromIconName is a wrapper around gtk_tooltip_set_icon_from_icon_name().