EnableExplicit

Define a
Define EventID
Define Quit

If OpenWindow(0,0,0,500,250,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  EditorGadget(1,10,10,480,200,0)
  For a=1 To 50
    AddGadgetItem(1,-1,"Teststring",0,0)
  Next
  ButtonGadget(2,390,220,100,20,"Nach oben scrollen",0)
Repeat
EventID=WaitWindowEvent()
If EventID=#PB_Event_Gadget
  Select EventGadget()
    Case 2
      SendMessage_(GadgetID(1),#EM_SCROLL,#SB_LINEDOWN,0)
  EndSelect
EndIf
If EventID=#PB_Event_CloseWindow
  Quit=1
EndIf
Until Quit=1
EndIf