public GraphDoc()
{
Name = "GraphDoc " + NextDocumentId();
//LinksLayer = Layers.CreateNewLayerBefore(Layers.Default);
LinksLayer = Layers.CreateNewLayerAfter(Layers.Default);
LinksLayer.Identifier = "Links";
LinksLayer.AllowSelect = true;
//Layers.CreateNewLayerAfter(Layers.Default).Identifier = "bottom";
Layers.CreateNewLayerBefore(Layers.Default).Identifier = "bottom";
MaintainsPartID = true;
IsModified = false;
//UndoManager = new GoUndoManager();
}