change glissando slope

[Federico Bruni]

Hi all

I cannot remember how can I adjust the slope of a glissando.
This is relevant when the two notes are very close and the glissando 
line could be "flat" and just over the staff line, as in this example:

%%%%%
\version "2.19.37"

myMusic = \relative {
 f'\glissando fis
 s1*4
}

\score {
 \new StaffGroup <<
   \new Staff { \clef "treble_8" \myMusic }
   \new TabStaff { \clef "moderntab" \new TabVoice \myMusic }
 >>
 \layout {
   indent = 0
   ragged-right = ##f
   \context {
     \Score
     \override Glissando.springs-and-rods = 
#ly:spanner::set-spacing-rods
     \override Glissando.thickness = #2
   }
 }
}
%%%%%


By the way, I think that the proper way to work around this problem 
should be added here:
http://www.lilypond.org/doc/v2.19/Documentation/notation/expressive-marks-as-lines.html

or in the relevant Snippets section.

Thanks in advance
Federico