defining custom contexts: child context doesn't work properly

[Janek Warchoł]

Hi,

I'm trying to create predefined custom contexts for specific
instruments, for example define a TenorStaff which has appropriate
instrumentName, clef, ambitus, etc.

Predefined staves work well, but i didn't manage to make custom voice
contexts work properly with them - despite using \defaultchild, wrong
context is created.

Here are the definitions that i have so far:
http://github.com/openlilylib/snippets/blob/master/templates/predefined-instruments/instrument-context-definitions.ily

Here is my testing file:
http://github.com/openlilylib/snippets/blob/master/templates/predefined-instruments/overriding-example.ly

Note that i can override the color of noteheads in AltoStaff by using
appropriate command in the \layout block, but if i try to do this for
SopranoVoice, nothing hapens.  Apparently soprano notes aren't placed
in a SopranoVoice, just in an ordinary Voice.

Any ideas?
Janek

PS since the files are placed in a repository on GitHub, you can edit
them online and send me suggested changes via GitHub interface, as
explained here http://github.com/openlilylib/snippets/blob/master/README.md