refining menu UI for empty submenus

[dharmaquark]

right now, when a submenu is empty, the parent menu item will open an empty/compressed submenu, or vertical bar (see screenshot below). This can get a little confusing in the UI, especially in cases where the submenu context is set dynamically and not known before runtime.

May be nice to add some visual indication that the submenu is empty (maybe disabling the parent menu item, or adding an 'Empty' or 'No Items' type row to the submenu that makes it clearer in the UI that the submenu is intentionally empty?)

Opening this issue to start a conversation around possible ways to refine the UI for explicitly empty/disabled submenus.
(@jasongrout and @ivanov for awareness)

[sccolbert]

I like this as a general idea.

For what it's worth, you could possibly implement this yourself right now with a custom Menu.IRenderer.