Procedure Thread(dummy)
  Repeat
    GetWindowRect_(GadgetID(1),re.RECT)
    GetCursorPos_(pt.POINT)
    If PtInRect_(re, pt\y << 32 + pt\x) = 1
      SetGadgetText(2,"MouseOver: Ja")
    Else
      SetGadgetText(2,"MouseOver: Nein")
    EndIf
    Delay(100)
  ForEver
EndProcedure

If OpenWindow(0,0,0,500,250,"Window",#PB_Window_SystemMenu|#PB_Window_ScreenCentered)
  ButtonGadget(1,10,10,100,20,"Test-Button",0)
  TextGadget(2,10,40,100,20,"",0)
  
  CreateThread(@Thread(),0)
Repeat : Until WaitWindowEvent() = #PB_Event_CloseWindow
EndIf