-As you can see in output = the example file "test.ly" there are a few problems left:
-- key undo (already in the Todo)
-- "wrong" transposition: e.g. \transpose d of fis-major = gis-major (better as-major?).
- The solution gis=as etc. would concern both note and key transposistion
+\header{ texidoc = "@cindex Transposition
+Transposing has also an effect key signature, if it is given using
+@code{\key}. If @code{keySignature} is set explicitly instead,
+the key signature is not transposed."