Stem length of beamed notes

[Francesco Napoleoni]

Hi everyone

While engraving the music in screenshot-source.png I’ve stumbled on a problem: 
I cannot adjust the stem height of the first couple of eighth notes to look 
like the printed version.

To be more specific: overriding the Stem.details.beamed-lengths does not work 
for me no matter which value I put between the parentheses. The relevant part 
is at line 6 of fragment.ly.

Any ideas?

Thanks in advance
Francesco Napoleoni

screenshot-source.png
Description: PNG image

fragment.ly
Description: Text Data

screenshot-lilypond.png
Description: PNG image