For full screen "main menus" I would have it on a layout for its own.
Layers should allow you to navigate between several "menu screens" to access different parts.
For an "ingame menu" (like pause), I would have it in a top layer in the game/level layout, and pause/make sure the rest of the game can't get accessed when the top layer (menu) is visible, so that only the top menu gets the user input.
(this can be done by adding some check system:is layer visible (top layer)/invert to the events of the game, system:is layer visible (top layer) for the events of the menu.
For concrete examples, I don't recall a specific one posted.
I hope this helps you nevertheless.