Adding separators to the context menu

Does the FILE TYPE EDITOR allow me to place underlines/separators into the context menu to help me break things up ?

Yes, the same way it is done with toolbar buttons: Either drag the lower item slightly away from the item above it or right-click the lower item and select 'begin a group'.

Right clicking on an item and selecting "begin a group" works for me. Alternatively dragging the menu item down slightly works fine as well.