#RequireAdmin #include <GUIConstantsEx.au3> Local $Handle, $Handle1, $Handle2, $return, $struct, $Struct1, $Struct2, $x, $y, $button1, $MSG GUICreate("multithread", 410, 360) $button1 = GUICtrlCreateButton("Start Me Up!", 15, 90, 90, 20) GUISetState() While 1 $MSG = GUIGetMsg() Select Case $MSG = $GUI_EVENT_CLOSE ExitLoop Case $MSG = $button1 $Handle1 = DllCallbackRegister("ThreadTest1", "int", "ptr") ;<---calls Func ThreadTest1($x)