Documentation or programming error?

[fiëé visuëlle]

Here: http://www.lilypond.org/doc/v2.9/Documentation/user/lilypond/ 
Font-selection.html
it says that make-pango-font-tree should be placed in \paper.
At least on my system with LilyPond 2.9.21 it works only in \layout.
Could someone test/correct this please?

BTW: What does the / in (/ staffsize 20) mean?

Greetlings from Lake Constance
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fiëé visuëlle
Henning Hraban Ramm
http://www.fiee.net
http://angerweit.tikon.ch/lieder/
http://www.cacert.org (I'm an assurer)

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