As I see it, there are a couple of possibilities here.
1) Within the gabc file use unjustified manual line breaks ('(Z)' < note capital letter). The staff lines will still run all the way across the page and the custos will be printed at the end of them, but the music will stop early. This will allow you to erase the lines and have the space you need in a post processing application. You can insert a manual custos before the line break ('(g+Z)' where g is the height of the custos) if you want to keep it. However, it should be noted that if you do this for successive lines, you will have a ragged line endings.
2) Encapsulate the score within a minipage environment. This allows you to dictate a uniform limit to the line length that is shorter than the page width. However, this will apply to the whole score, not just the first few lines, and the score must fit on one page. You could work around this by splitting your score into two, and only enclosing the first part within the minipage environment.
Both of these solutions have their problems, as pointed out above, and like you I think that it should be possible to manipulate the line width in a similar manner as is done for the initial, but I could not get this to work. The line width is controlled by the variable \grelinewidth and the length of the staff lines by \grestafflinewidth. Inserting '[ev:\grechangedim{\grestafflinewidth}{4in}]' into a gabc file would cause the stafflines to shorten from the next manual linebreak on, but the sylables paid no attention to this and changing \grelinewidth had no effect. At this point I don't know why this doesn't work and include it here in case somebody else knows a bit more about the behavior of these dimensions and can shed some further light on the subject.
✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝ Br. Samuel, OSB (R. Padraic Springuel) PAX ☧ ΧΡΙΣΤΟΣ _______________________________________________ Gregorio-users mailing list [email protected] https://mail.gna.org/listinfo/gregorio-users
