private void OnInputFilterGotFocus(object sender, RoutedEventArgs e)
 {
     if (this.defaultText == InputFilterText.Text)
     {
         InputFilterText.Text = "";
         InputFilterText.SetValue(TextBox.ForegroundProperty, DependencyProperty.UnsetValue);
     }
 }
 internal void FocusTextBox()
 {
     InputFilterText.Focus();
     InputFilterText.SelectAll();
 }