Vertical position of markups

[James Worlton]

Hello all,

Question: Is it possible to specify the absolute position of
header block items?

Explanation: I have adapted the great macro set from the
LSR Ready-to-Use LilyPond Macros by Nicolas Sceaux:
http://lsr.dsi.unimi.it/LSR/Item?id=368 
for my own scores' title pages. One thing I've noticed is that
even though you may specify \abs-fontsize for each of the
header elements, any \vspace values between them are
dependent on the #(set-global-staff-size) value.

I have set up all the elements and vertical spacing so
everything appears correctly at global staff size 17. But if
I need a different staff size, all of the positioning gets
proportionally squished or expanded.

I would like to be able to exactly specify on the title page
where each header element should appear independent of
the global staff size. Is this possible?

Thanks,
James Worlton