There 3 steps below:

1.Hold left button of mouse and move mouse to define a new node
2.Release button
3.NodeCreated event will be fired and my code will do something.

The type of new node is XXX (I mean that it is a new type).
After created this node user can not resize it by mouse.
Because I write these code below in the construction method

this.Constraints.MinHeight = EMActorShape.DefaultHeight;
this.Constraints.MinWidth = EMActorShape.DefaultWidth;

It can work well, user can not resize it exactly. But in the step
1, when use define it, user still can use mouse to resize it. In the
NodeCreated event handler, the size of new node is as same as the size
when user release left button.

So my question is how to stop user resize a new node when use define
it ?

Thanks a lot.