I have been using the dragSelectingTool to drag and create a rectangle to select the items within them.
this.diagram.toolManager.dragSelectingTool.box =
(go.Part,
{ layerName: 'Tool', selectable: true },
(go.Shape, ‘Rectangle’,
{ name: ‘SHAPE’, fill: null, stroke: ‘dodgerblue’, strokeWidth: 2 })
);
However, when we select multiple items on the screen and release the mouse key, it only selects the last item on the screen. What can I do to resolve the issue?