# Optimized `GroupedArray` to use `Sprite::context_index` and avoid using `index_of`
private class GroupedSprites
	super GroupedArray[Sprite]

	redef fun add(item)
	do
		var index = super
		item.context_index = index
		return index
	end

	redef fun remove(item) do remove_at(item, item.context_index)
end