There is a conceptual conflict between the use of content to layout nodes in a Container, and the use of content to control z-ordering.

As a simple example, if you have a Tile layout the order you insert the Nodes into content controls the left-to-right and top-to-bottom order of the Nodes. As a result, when you call toFront or toBack on one of the nodes in the Tile, it will not only change the z-order, but also move the position of the Node (which is usually not desirable).

It seems like the z-order of Nodes should be independent of the order they are stored in the content sequence.