Resets the undo flag of an edit control
#include <GuiEdit.au3>
_GUICtrlEdit_EmptyUndoBuffer ( $hWnd )
| $hWnd | Control ID/Handle to the control | 
The undo flag is automatically reset whenever the edit control receives a _GUICtrlEdit_SetText().
_GUICtrlEdit_CanUndo, _GUICtrlEdit_Undo
#include <GUIConstantsEx.au3>
#include <GuiEdit.au3>
#include <MsgBoxConstants.au3>
Example()
Func Example()
    Local $idEdit
    ; Create GUI
    GUICreate("Edit Empty Undo Buffer", 400, 300)
    $idEdit = GUICtrlCreateEdit("This is a test" & @CRLF & "Another Line", 2, 2, 394, 268)
    GUISetState(@SW_SHOW)
    _GUICtrlEdit_AppendText($idEdit, @CRLF & "Append to the end?")
    MsgBox($MB_SYSTEMMODAL, "Information", "Can Undo: " & _GUICtrlEdit_CanUndo($idEdit))
    _GUICtrlEdit_EmptyUndoBuffer($idEdit)
    MsgBox($MB_SYSTEMMODAL, "Information", "Can Undo: " & _GUICtrlEdit_CanUndo($idEdit))
    ; Loop until the user exits.
    Do
    Until GUIGetMsg() = $GUI_EVENT_CLOSE
    GUIDelete()
EndFunc   ;==>Example