vertical spacing of footnotes

[Werner LEMBERG]

Consider this example.

```
#(set-default-paper-size "a8landscape")

\book {
  \header { tagline = ##f }
  \markup "time-based footnotes"
  \relative c'' {
    r1 |
    \footnote #'(-0.5 . -1) "Meter change." Staff.TimeSignature
    \time 3/4
    \footnote #'(1 . -1) "Chord stem." Stem
    <c e g>4 q q
    \footnote #'(-0.5 . 2) "Bar line." Staff.BarLine
    q q
    \footnote #'(0.5 . -1) "Key change." Staff.KeySignature
    \key c \minor
    q
  }
}
```

As can be seen in the attached image, the vertical distances between
the footnotes are not identical.  What is the recommended way to fix
this?


    Werner