MousePosition usually specifies where the adjustment handle has been dropped, but since in multiple selection there isn't any handle associated with the operation, the argument is not set. You can always find the current mouse position as below:

Point screenPos = Control.MousePosition;
Point clientPos = diagView.PointToClient(screenPos);
PointF diagPod = diagView.ClientToDoc(clientPos);

I hope that helps,
Stoyan

This is just a minor inconvenience, while the decoupling has some great advantages, at least from our point of view. Independence from Windows Forms lets you use the diagramming API from services or console applications, e.g. to do some batch processing. It will also let us create WebForms.DiagramView and Gtk.DiagramView components for use on other platforms, while reusing everything from the Diagramming, Layout, Import and Export namespaces.

We can implement a MousePosition argument for multiple-selection as well. In that case it might be misleading to specify it in the NodeModified event, when the node could be far away from the mouse. So perhaps we'll add it to the SelectionMoved args.

Stoyan