How to apply a tweak once to PostEvents of a function?

[Thomas Morley]

Hi,

let's assume I want to return two post-events by an event-function.
How to do, so that a \tweak before is applied only to the first of the
two post-events, like it is done when everything is spelled out?

Here some code I have so far:

tst =
#(define-event-function ()()
  (make-music 'PostEvents 'elements
    (list
      (make-music 'StringNumberEvent 'string-number 3)
      (make-music 'FingeringEvent 'digit 1))))

{
  %% function
  b\tweak color #red \tst
  %% spelled out
  b\tweak color #red \3 -1
}

Thanks,
  Harm