private void OnNameChanged(object sender, TextChangedEventArgs e) { CheckButtonStates(); if (TextBoxName.Text.IndexOfAny(InvalidNameChars) >= 0) { TextBoxName.Background = Brushes.Red; TextBoxName.ToolTip = Walkabout.Properties.Resources.AccountNameValidChars; ButtonOk.IsEnabled = false; } else { TextBoxName.ClearValue(TextBox.BackgroundProperty); } }