private void SearchTextBox_PreviewKeyDown(object sender, KeyEventArgs e) { if (e.Key != Key.Enter) { return; } if (popup.IsOpen) { popup.IsOpen = false; return; } SearchViewModel svm = DataContext as SearchViewModel; if (svm != null) { if (!svm.IsFound) { return; } if (!svm.Continue()) { popup.IsOpen = true; } } }