If OpenWindow(0,0,0,500,250,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  StringGadget(1,10,10,100,20,"Teststring",#ES_NOHIDESEL)
  
  SendMessage_(GadgetID(1),#EM_SETSEL,0,-1)
Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf