code: public void onMouseDown(MouseDownEvent event) {
  		FeatureTransaction featureTransaction = getFeatureTransaction();
  		if (featureTransaction != null && parent.getEditMode() == EditMode.DRAG_MODE
  				&& event.getNativeButton() != Event.BUTTON_RIGHT) {
  			String targetId = getTargetId(event);
  			if (TransactionGeomIndexUtil.isVertex(targetId)) {
  				dragTargetId = targetId;
  				if (dragTransaction == null) {
  					dragTransaction = (FeatureTransaction) featureTransaction.clone();
  				}
  				mapWidget.render(featureTransaction, RenderGroup.VECTOR, RenderStatus.DELETE);
  				mapWidget.render(dragTransaction, RenderGroup.VECTOR, RenderStatus.ALL);
  				createTempLines(featureTransaction, event);
  			}
  		}
  	}
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