private bool TextChange(TextChangedType type, string text)
 {
     var e = new PreviewTextChangedEventArgs(PreviewTextChangedEvent, type, text);
     OnPreviewTextChanged(e);
     return e.Handled;
 }
 protected virtual void OnPreviewTextChanged(PreviewTextChangedEventArgs e)
 {
     RaiseEvent(e);
 }
 private void TextBox_OnPrevieTextChanged(object sender, PreviewTextChangedEventArgs e)
 {
     MessageBox.Show(TextBox.Text);
 }