public override void FinishedLaunching(NSObject notification)
{
mainWindowController = new MainWindowController ();
var drawingView = new DrawingView(mainWindowController.Window.ContentView.Bounds);
mainWindowController.Window.ContentView.AddSubview(drawingView);
mainWindowController.Window.MakeKeyAndOrderFront (this);
mainWindowController.Window.MakeFirstResponder(drawingView);
}