When user move selected shape/shapes, the default behave is to show a visual effection. In my case, I want to show a rectangle, just a rectangle. Is there any easy way to do it? such as to set a value to a property.

Thanks.

Thanks for reply. How about several shapes ？such as 2 nodes and 2 links。

Thanks for you reply. Yes, I tried and can implement what I want. But the point is I am not sure this is a best way and it is stable enough. Base on some questions that asked you, I know that if user select several shapes and try to move it, then I only can customize my InteractionState object in OnMouseMove method of ModifyBehavior. So far there are three choices:

1. Without calling base.OnMouseMove and create my InteractionState object:
protected override void OnMouseMove(Point mousePosition)
{
     InteractionState state = this.Diagram.Interaction;
     PointF pointDoc = this.DiagramView.ClientToDoc(mousePosition);
     
     if (IsReadyToMoveMultiShapes(pointDoc, state) == true)
     {
           this.Diagram.Interaction = new InteractionState(this.trackerShape, 8, MindFusion.Diagramming.Action.Modify);
           this.Diagram.Interaction.MouseMoved = true;
           this.Diagram.Interaction.Start(pointDoc, this.Diagram);
     }

     ...      // other code here
}
But this way cause a exception is thrown

2. Calling base.OnMouseMove and create my InteractionState object:
protected override void OnMouseMove(Point mousePosition)
{
     InteractionState state = this.Diagram.Interaction;
     PointF pointDoc = this.DiagramView.ClientToDoc(mousePosition);

     if (IsReadyToMoveMultiShapes(pointDoc, state) == true)
     {
           base.OnMouseMove(mousePosition);

           this.Diagram.Interaction = new InteractionState(this.trackerShape, 8, MindFusion.Diagramming.Action.Modify);
           this.Diagram.Interaction.MouseMoved = true;
           this.Diagram.Interaction.Start(pointDoc, this.Diagram);
     }
     ...      // other code here
}
This way can work but when user is moving shape there are some problems, I fix all expcept one. The left problem is when user is moving trackerShape, trackerShape covers these links that connect to selected shapes. So I choose third way

3. Without calling base.OnMouseMove, create my InteractionState object and move trackerShape by myself:
protected override void OnMouseMove(Point mousePosition)
{
     InteractionState state = this.Diagram.Interaction;
     PointF pointDoc = this.DiagramView.ClientToDoc(mousePosition);

     if (IsReadyToMoveMultiShapes(pointDoc, state) == true)
     {
           this.Diagram.Interaction = new InteractionState(this.trackerShape, 8, MindFusion.Diagramming.Action.Modify);
           this.Diagram.Interaction.MouseMoved = true;
           this.Diagram.Interaction.Start(pointDoc, this.Diagram);
     }
     else if (state != null &&
            (state.CurrentItem is TrackerNode) == true &&
            state.Action == MindFusion.Diagramming.Action.Modify)
     {
           TrackerNode item = (TrackerNode)state.CurrentItem;

           rect.X = pointDoc.X - state.StartPoint.X + item.OriginX;
           rect.Y = pointDoc.Y - state.StartPoint.Y + item.OriginY;
           item.Move(rect.X, rect.Y);
     }

     ...      // other code here
}
This is the way I choose and looks can work well so far. But compare with your code, your code is simple, I like it.

So could you give me a better way that is simpler and stabler to do same thing ? We will buy new version maybe include source code sooner or later. Because of:
1. This is a good production
2. we will not choose other production and spend extra time to learn new SDK.

So do not worry we are stable customers. Thanks a lot.

Thanks. After spending hours I made it. But I found a new problem. Because it is a new topic so I post a new thread.