thanks for the explanation.
> Why wouldn't it? Separate expressions in a \line (which is what a
> top-level markup is implicitly wrapped in) are separated by word space.
> That's totally normal. If you want to join some elements, use \concat,
> like with ...
You explanation and example were helpful. I suggest to add them to
this page:
http://www.lilypond.org/doc/v2.17/Documentation/notation/formatting-text
% this
\markup { \huge \line { fee fie foe fum } }
% or that will separate the expressions with _normal_ size spaces
\markup { \huge { fee fie foe fum } }
% or
\markup { \huge fee\huge fie\huge foe\huge fum }
% whereas this will use _huge_ spaces between words.
\markup { \huge "fee fie foe fum" }