I found this example on an edit control:
#include <GuiConstantsEx.au3>
#include <WindowsConstants.au3>
#include <EditConstants.au3>
#include <GuiMenu.au3>
#include <Constants.au3>
#include <WinAPI.au3>
Global Enum $idOpen = 1000, $idSave, $idInfo
$hGUI = GUICreate("Test", 300, 200)
$Edit1 = GUICtrlCreateEdit("", 10, 10, 280, 150, BitOR($WS_HSCROLL, $WS_VSCROLL, $ES_MULTILINE))
$hMenu = _GUICtrlMenu_CreatePopup()
_GUICtrlMenu_AddMenuItem($hMenu, "Open",