"Sub-menu" in ContextMenu

I’m not really finding anything in the docs, but is there any way to create a “submenu” inside of a custom ContextMenu?

I’m not sure exactly what it’s called, so I attached a screenshot.

EDIT: Oh, and one more thing. Is there any way to make checkboxes/radio buttons in context menus? Otherwise I could just list all items like this:

[IMG]file:///C:/DOCUME%7E1/Andreas/LOCALS%7E1/Temp/moz-screenshot.png[/IMG]200%
150%
100% (current)
50%