void CheckAddressTextField() {
InvokeOnMainThread(delegate {
string error = this.Controller.CheckAddPage(AddressText.StringValue);
if (string.IsNullOrEmpty(error)) {
AddressHelp.StringValue = string.Empty;
} else {
AddressHelp.StringValue = Properties_Resources.ResourceManager.GetString(error, CultureInfo.CurrentCulture);
}
});
}