You cannot do this directly, but there is a trick that can help you move the end point of the connector after cancelling the connection. The idea is to use a System.Windows.Forms.Timer and move the plug in a direction of your choice in the timer's Tick event. Here's an example:
document.EventSinkService.Connecting += new ConnectionCancelEventHandler(OnEventSinkServiceConnecting);
...
private void OnEventSinkServiceConnecting(NConnectionCancelEventArgs args)
{
NPlug plug = args.Document.GetElementFromUniqueId(args.UniqueId1) as NPlug;
NPort port = args.Document.GetElementFromUniqueId(args.UniqueId2) as NRotatedBoundsPort;
args.Cancel = true;
Timer timer = new Timer();
timer.Interval = 100;
timer.Tag = plug;
timer.Tick += new EventHandler(OnTimerTick);
timer.Start();
}
private void OnTimerTick(object sender, EventArgs e)
{
Timer timer = (Timer)sender;
timer.Stop();
NPlug plug = (NPlug)timer.Tag;
plug.Location = new NPointF(plug.Location.X, plug.Location.Y - 50);
}