Putting horizontal brackets at a fixed y-position

[sven]

Is there already a non-hackish way of putting horizontal brackets (voltas and
analysis brackets) at a *fixed* y-position unaffected by the bracketed music?
If not I'm willing to sponsor such a feature that for both volta brackets and
analysis brackets lets me do, for instance

\override HorizontalBracket #'fixed-position = #'(2 . 3) % use octave and note
pos

or perhaps using the padding property together with a flag. Now the bracket will
all be put at that position, even if the music overlaps them.

How about that? And I actually consider it a bug that Lilypond doesn't do this
as default.

-- 
Sven Axelsson