I've recreated an example of HorizontalLayout from http://feathersui.com/examples/layout-explorer/
1) "Quads inside the parent container"
Initially a parent container(ScrollScreen) with horizontal layout contains quads. The elastic edges work very nice.
2) "Quads inside the additional container"
When I add an additional container (ScrollContainer) with HorizontalLayout to the parent and assign AnchorLayout or VerticalLayout for the parent - elastic edges don't work.
I've set width/height for the additional container, set horizontalScrollPolicy for the both containers, checked all properties related to "elasticity" - it still doesn't work. It works only when the type of the additional container is set to ScrollScreen