Add independent control of thickness and offset for underline markup (issue1347041)

[n . puttock]

Hi Kieren,

I don't think we can remove the link between 'line-thickness and
underline offset, since it should scale based on staff-size.  At small
staff-sizes, 'line-thickness gets progressively larger, which matches
the thicker underline with a slightly bigger gap.

What you could do instead is leave out the default value for offset and
keep the existing behaviour unless the user sets offset (if it's unset,
it will return #f).

Cheers,
Neil


http://codereview.appspot.com/1347041/diff/1/2
File scm/define-markup-commands.scm (right):

http://codereview.appspot.com/1347041/diff/1/2#newcode280
scm/define-markup-commands.scm:280: #:properties ((thickness 1) (offset
0.5))
I think this default for offset is too large.

http://codereview.appspot.com/1347041/diff/1/2#newcode301
scm/define-markup-commands.scm:301: (y (* -1 offset))
Simpler:

(- offset)

http://codereview.appspot.com/1347041/show