#Include <WindowsConstants.au3>
$hForm = GUICreate('MyGUI', 400, 400, -1, -1, -1, $WS_EX_TOPMOST)
$Button = GUICtrlCreateButton('MsgBox', 165, 366, 70, 23)
GUISetState()
While 1
$Msg = GUIGetMsg()
Switch $Msg
Case -3
ExitLoop
Case $Button
MsgBox(0, '', '', 0, $hForm)
EndSwitch
WEnd