footnote and rests/rehearsal marks

[Federico Bruni]

I'm trying to use \footnote for the first time.
Can I attach a footnote to a rest or a rehearsal mark?

I've made some tries with no success:

\relative c' {
  \footnote #'(0.5 . -2)
  \markup { This works }
  a'2 b

  \footnote #'(0.5 . 1)
  \markup { doesn't work }
  R1

  \footnote #'(0.5 . 1) #'RehearsalMark
  \markup { doesn't work either }
  \mark \markup { Note 2 }
  c1

}