PageTrackerTarget
"last-button"
{}
{ /ClientPage {
    CurrentEvent /ClientData get begin 
      PageCount 0 eq PageNumber PageCount 1 sub eq or
    end {deactivate} {activate} ifelse 
  } def
  /ClientUp { /last-page PileDict ContentsPileID get /Win get send } def
  /ItemPath {rr} def }