render_layer for sticker

[evildogbot100]

I would like for sticker to have render_layer so I can render sticker behind the object it sticks to. Would like if this is extended to all animation, but just sticker is fine. My idea was to make an idle animation for enemy units that is decoupled from its actual movement, which I decided to investigate whether sticker can be used for this purpose.

[evildogbot100]

Apparently, my use case can be satisfied using LuaRendering. However, the idea of more control over render_layer itself might have some use in other case