This extension is a layer system designed to reduce draw calls without modifying your display list structure.
It's particularly useful if you have several items that not overlap and makes several draw calls each.
For example, a list of items composed of an image background and a bitmap font text (from another texture), that make 2 draw calls each. This container can render first all backgrounds, then all texts, rendering the whole list in only 2 draw calls thanks to starling batching system.
The idea is really simple, this container hides objects that are not in layer 1, renders itself, then shows items from layer 2 and hides others, render again, etc...
The rendering is a little heavier for CPU, but if used correctly, it can significantly reduce draw calls and so increase rendering speed.
If you got any ideas about it, I would be happy to hear them 🙂