public UMLObjectCollection(Diagram diagram)
{
if (diagram == null)
throw new ArgumentNullException();
this.diagram = diagram;
models = diagram.Models;
connections = diagram.Connections;
}
/// <summary>
/// Create new blank diagram
/// </summary>
private void CreateNewDiagram()
{
Diagram diagram = new Diagram();
if (Project.Current == null)
CreateNewPorject();
Project.Current.Children.Add(diagram);
}