Flat / Inline Submenus

Hi,
I don't know if this has been asked before - I didn't find it.

It would be sweet if I could make the items of a submenu to show "inline" in the parent menu.

Example. Consider this menu tree:

Code:

A
  A.1
  A.2
B (set as "inline" or "flat")
  B.1
  B.2
    B.2.1
    B.2.2
  B.3
C
  C.1
  C.2

This would result in the following menu display on the first level:

Code:

A > (A.* popout submenu)
[caption saying "B"]
B.1
B.2 > (B.2.* popout submenu)
B.3
[separating line]
C > (C.* popout submenu)

One use case would be that you could embed "My computer" as an inline menu, where you can still add plugins and other things in the parent menu.