EnableExplicit

Define a

If OpenWindow(0,0,0,500,250,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  EditorGadget(1,10,10,480,230,0)
  For a=1 To 5
    AddGadgetItem(1,-1,"Testzeile",0,0)
  Next
  
  SendMessage_(GadgetID(1),#EM_SETSEL,0,9)
  SendMessage_(GadgetID(1),#EM_SETFONTSIZE,-5,#Null)
  SendMessage_(GadgetID(1),#EM_SETSEL,20,29)
  SendMessage_(GadgetID(1),#EM_SETFONTSIZE,5,#Null)
  SendMessage_(GadgetID(1),#EM_SETSEL,30,39)
  SendMessage_(GadgetID(1),#EM_SETFONTSIZE,10,#Null)
  SendMessage_(GadgetID(1),#EM_SETSEL,40,49)
  SendMessage_(GadgetID(1),#EM_SETFONTSIZE,15,#Null)
  SendMessage_(GadgetID(1),#EM_SETSEL,49,49)
Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf