EnableExplicit

Define a

If OpenWindow(0,0,0,500,250,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  PanelGadget(1,10,10,480,230)
    For a=1 To 15
      AddGadgetItem(1,-1,"Paneltab "+Str(a),0,0)
    Next
  CloseGadgetList()
  SetWindowLongPtr_(GadgetID(1),#GWL_STYLE,GetWindowLongPtr_(GadgetID(1),#GWL_STYLE)|#TCS_MULTILINE)
  SetGadgetState(1,0)
  
  MessageRequester("","Anzahl der Panel-Reihen: "+Str(SendMessage_(GadgetID(1),#TCM_GETROWCOUNT,0,0)),0)
Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf