How to set style of parent object in child object

GoJS
1 
$("CheckBox", "choice",
                    {
                        row: 2,
                        column: 0,
                        "Button.width": 20,
                        "Button.height": 20,
                        "ButtonBorder.figure": "Circle",
                        "ButtonBorder.stroke": "blue",
                        "ButtonIcon.figure": "Circle",
                        "ButtonIcon.fill": "blue",
                        "ButtonIcon.strokeWidth": 0,
                        "ButtonIcon.desiredSize": new go.Size(10, 10)
                    },
                    $(go.TextBlock, "is hidden"),
                    {
                        "_doClick": function (e, obj) {

                            console.log( obj.findObject('SHAPE') ); // null ? why ?

                            let hiddenItems = document.querySelector('.hidden-items');
                            let choice = obj.part.data.choice;

                            obj.part.data.draggable = !!obj.part.data.choice;

                            if (choice) {
                                let li = document.createElement('li');
                                li.setAttribute('data-obj', JSON.stringify(obj.part.data));
                                li.classList.add(`item-hidden-${obj.part.data.key}`);
                                li.textContent = obj.part.data.name;
                                hiddenItems.appendChild(li);
                            } else {
                                let li = document.querySelector(`.item-hidden-${obj.part.data.key}`);
                                if (li) {
                                    li.remove();
                                }
                            }
                        }
                    }
                ),

$(go.Shape, "Rectangle",
            {
                name: "SHAPE", fill: "white", stroke: null,
                portId: "", fromLinkable: true, toLinkable: true, cursor: "pointer"
            }),

console.log( obj.findObject(‘SHAPE’) ); // null ? why ? find only in children of choice ?
and how to change SHAPE opacity on choice click ?
how to change choice title

Please, help me.
Thanks

2

You can examine the definition of “CheckBox”, “CheckBoxButton”, and “Button” in http://gojs.net/latest/extensions/Buttons.js.

There you will see that there is no GraphObject named “SHAPE”, which is why your call to Panel.findObject returned null.

You can tell what some of the named objects are from the property settings that you are using: “Button”, “ButtonBorder”, and “ButtonIcon”.