Z-Index

In the 2D context, Z-Index, or depth, only exists in the context of the Layers object.

public static function setZIndex(obj: h2d.Object, idx: Int, ?parentLayer: Layers): Layers {
    if(parentLayer == null){
        parentLayer = new Layers(obj.parent);
        obj.parent.addChild(parentLayer);
    }
    parentLayer.add(obj, idx);
    return parentLayer;
}

Scenes are layers, so you can just use those.

	setZIndex(obj, 100, state.scene);

The Heaps API for z-index manipulation is unintuitive and would benefit from a dedicated depth field on objects.

From the user side, a more complex management object might be required for comprehensive manipulation.