async void HandleSelectedDocumentsChanged (object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
{
if (Editing) {
UpdateEditingForSelection ();
return;
}
if (selecting) {
if (docsView.SelectedDocuments.Count == 1) {
await PerformActionOnDocument (docsView.SelectedDocuments [0]);
}
}
}