zIndex on line 267 in web/script/domWidget.js

Here is the surrounding of line 267 in web/script/domWidget.js
```javascript
Object.assign(element.style, {
transformOrigin: "0 0",
transform: scale,
left: `${transform.a + transform.e}px`,
top: `${transform.d + transform.f}px`,
width: `${widgetWidth - margin * 2}px`,
height: `${(widget.computedHeight ?? 50) - margin * 2}px`,
position: "absolute",
zIndex: app.graph._nodes.indexOf(node),
});
```
Basically, I'm questionning the usefulness of `zIndex: app.graph._nodes.indexOf(node),`.
I'm not completely sure why this is there, but here is the behavior with line 267 uncommented:

https://github.com/comfyanonymous/ComfyUI/assets/1372055/a95acb1b-c5e4-49d7-8918-a99dd52fb31a

and now with the line 267 commented:

https://github.com/comfyanonymous/ComfyUI/assets/1372055/8af56e52-ec0c-45d8-b394-179c0df72f3c

Again, I'm not sure what line 267 is trying to achieve, but the behavior without it seem more satisfying.