\version "2.19.47"

funcA =
#(define-music-function (mus)(ly:music?)
   #{
     #mus
   #})

funcB =
#(define-music-function (mus)(ly:music?)
   #{
     {
       #mus
     }
   #})

{
  % funcA: point-and-click points to function invocation
  \funcA c'
  % funcB: point-and-click points to music
  \funcB d'
  % funcA: *now* point-and-click *also* points to music
  \funcA { e' }
}