Improve TabStaff readability : solid white box under fret number

[SPORN David]

Hello,

When using TabStaff, fret numbers are written over a line staff. It's 
still readable, but I think the result would be better if the line staff 
could be locally erased (and in the magazine, tablatures are displayed 
this way)

The most obvious way to me would be to draw a solid white box 
(corresponding to the number's box) before drawing the fret number. I 
saw in the archive that color support is not planed because usually 
music sheets are printed in black on white, but I think that supporting 
the white color would be appropriate.

But doing it by tweaking the tex script generated by lilypond is not an 
option for me, I would prefer do the tweaking in the lilypond script, 
like overriding an engraver print function with something like 
"(make-box-markup (number->string mark))" (snippet taken from "5.15.3 
Rehearsal marks").

Thanks in advance

--
David SPORN (Poste 4336)
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MICROPOLE UNIVERS
100 rue Lafayette - 75010 Paris
Tél. + 33 1 42 47 42 47 - Fax + 33 1 42 47 40 00
www.micropole-univers.com
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