%% Two scores are needed to separately control MIDI and notation
%% output.
\score {
  \unfoldRepeats {
    <<
      \AllMusicMIDI
      \new DrumStaff { \click }
    >>
  }
  \midi {}
}

\score {
  %% Always unfold repeats in the big score.  The individual parts can
  %% have repeats as they wish.
  \unfoldRepeats { \AllMusic }
  \layout {
    \context {
      %% add the RemoveEmptyStaffContext that erases rest-only staves
      \Staff \RemoveEmptyStaves
    }
    \context {
      \Score
      \numericTimeSignature
      markFormatter = #format-mark-box-alphabet
      %% Remove all-rest staves also in the first system
      \override VerticalAxisGroup.remove-first = ##t
      %% If only one non-empty staff in a system exists, still print the starting bar
      \override SystemStartBar.collapse-height = #1
    }
  }
}