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

[Kieren MacMillan]

Hi Carl,

> Couldn't we define the offset as a multiple of 'line-thickness, instead of
> an absolute value?  That's how fret diagrams are scaled.

Sounds good to me!
To be clear, 'line-thickness and the thickness property of \underline are 
[potentially] two different independent values, right?

Cheers,
Kieren.