Oder ganz ohne Includes:
[autoit]
$hGui = GUICreate("Test", 400, 400)
$hEdit = GUICtrlCreateEdit("Zeile 0" & @CRLF & "Zeile 1" & @CRLF & "Zeile 2" & @CRLF & "Zeile 3", 10, 10, 380, 380)
GUISetState()
While GUIGetMsg() <> -3
ToolTip(ControlCommand($hGui, '', $hEdit, "GetCurrentLine", ""))
WEnd