Manual Staff switches don't appear to work

[Sandy Scott]

Not quite sure what the ettiquite for posting a bug that is quite probably my
incompetence, but I'll just straight to it:

This is the code from the Manual Staff Switches Page, with a few very small 
changes (added the version comment and also put some notes in the voice) to 
make it produce some output:

*******************************************
\version "2.10.0"
<<
  \new Staff = "up" {
    \skip 1 * 10  % keep staff alive
    }
  \new Staff = "down" {
    \skip 1 * 10  % idem
    }
(insert two "greater-than" signs here*)
\new Staff = down
  \new Voice {g a b c \change Staff = up d e fis g }
*******************************************

However, contrary to my expectations, this produces 3 staves, not 2 - the top 
two are blank and the third contains the notes, but obviously without any staff 
changes.

Is this a bug, a problem with the Docs, or just me being stupid?

Sandy Scott
*PS. Is there a tidier way of getting round the top-posting filter?