How can i save state of Panel Expanded?

How can i save state of Panel Expanded?

PanelExpanderButtons

new go.Binding(“visible”).makeTwoWay() …can not work

I just tried adding exactly that Binding to the IVR Tree sample, http://gojs.net/latest/samples/IVRtree.html, and it worked exactly as I thought it would, and as I think you expect it to.

                // with the list data bound in the Vertical Panel
                $(go.Panel, "Vertical",
                  {
                    row: 1, name: "COLLAPSIBLE",  // identify to the PanelExpanderButton
                    padding: 2,
                    stretch: go.GraphObject.Horizontal,  // take up whole available width
                    background: "white",  // to distinguish from the node's body
                    defaultAlignment: go.Spot.Left,  // thus no need to specify alignment on each element
                    itemTemplate: actionTemplate  // the Panel created for each item in Panel.itemArray
                  },
                  new go.Binding("visible").makeTwoWay(),
                  new go.Binding("itemArray", "actions")  // bind Panel.itemArray to nodedata.actions
                )  // end inner Vertical Panel

Wow!!! Awesome!Thank You!!