public override void OnNodesModified()
{
base.OnNodesModified();
// When Dynamo is shut down, the workspace is cleared, which results
// in Modified() being called. But, we don't want to run when we are
// shutting down so we check that shutdown has not been requested.
if (DynamicRunEnabled && EngineController != null)
{
DynamoModel.OnRequestDispatcherBeginInvoke(Run);
}
}