How to prevent SelectionChanged Mutilple occur!

GoSilverlight V1.224

In Diagram
SelectionChanged event multiple occur when I select multiple node
using mouse drag range area section.
I want to occur SelectionChanged event only once.
How to solve it.

Instead of defining a Diagram.SelectionChanged event handler, I suggest you replace the Diagram.DragSelectingTool with one that overrides the SelectInRect method.

public class CustomSelectingTool : DragSelectingTool { public override void SelectInRect(Rect r) { base.SelectInRect(r); . . . do what you want . . . } }
And install this tool via:

myDiagram.DragSelectingTool = new CustomSelectingTool();

or the same thing in XAML.