When I select multiple items from Palette and drop them to the canvas area. If overlaps one with another. Is there any way to give some spacing between the nodes.
Arrangement of nodes in a diagram is the responsibility of the Diagram.layout. What are you using for the layout?
If you have not specified any layout because you want the user to position all nodes manually, and you only want to handle this specific case of dropping from a Palette to the Diagram, then you can implement an “ExternalObjectsDropped” DiagramEvent listener that positions the nodes in the DiagramEvent.subject collection. You’ll need to decide exactly what policy you want to implement for positioning those nodes.