code: private Coordinate getOrigin(HumanInputEvent<?> event) {
  		// Get the original location for the lastly selected index:
  		if (lastSelection != null) {
  			try {
  				return service.getIndexService().getVertex(service.getGeometry(), lastSelection);
  			} catch (GeometryIndexNotFoundException e) {
  			}
  		}
  
  		// Backup plan: mouse location.
  		return getLocation(event, RenderSpace.SCREEN);
  	}
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