another skyline problem

[Werner LEMBERG]

Consider this input:

  {
  \once \override DynamicText #'X-offset = #'-5.0
  %\once \override DynamicText #'Y-offset = #'5.0
    c\ff
  }

  \paper {
    ragged-right = ##t
  }

As can be seen in the attached image, lilypond doesn't move the ff
symbol up -- this is the right action.  However, if you comment out
the line overriding the Y-offset property you can see that it has no
effect, which is problematic.  I'm not sure how this can be solved
elegantly.  Perhaps it's necessary to give Y-offset a new meaning for
grobs which are floating below and above the staff, something like:
`pretend that the parent's vertical position is moved by that amount'.


    Werner