> This should make a balloon text, [...]
There is no bug. As the documentation says, `\balloonText` only works
within chords. If you replace
```
hh1-\balloonText #'(1 . 1) \markup { "I'm a note head" }
```
with a single-note chord
```
<hh-\balloonText #'(1 . 1) \markup { "I'm a note head" } >1
```
you get the desired result.
Werner
