protected virtual void OnDiagramRequest(DiagramEventArgs e) {
     EventHandler<DiagramEventArgs> handler = DiagramRequest;
     if (handler != null) {
         handler(this, e);
     }
 }
 private void SchemaModel_DiagramRequest(object sender, DiagramEventArgs e) {
     try {
         this.CreateTabbedDocument(e.Table, e.Type);
     }
     catch (Exception ex) {
         ExceptionDialog.HandleException(ex);
     }
 }