Edit verweigert eingabe (maximale Anzahl der Zeilen überschritten?)

#include <WindowsConstants.au3>
#include <EditConstants.au3>
#Include <GuiEdit.au3>
#include <Misc.au3>
#include <Constants.au3>
#include <GUIConstantsEx.au3>
#include <ScrollBarConstants.au3>

Global $iHoehe_Max = 900
Global $iBreite_Max = 900
Global $iHoehe_Min = 300
Global $iBreite_Min = 300

Global $stitle = "Cmd for easy Copy & Paste"
Global $hdll = DllOpen("user32.dll")

$hWindow = GUICreate($stitle,$iBreite_Min,$iHoehe_Min,"","",BitOR($WS_SIZEBOX,$WS_SYSMENU,$WS_MINIMIZEBOX,$WS_MAXIMIZEBOX,$WS_CAPTION))
GUISetBkColor(0x000000)
GUICtrlSetDefColor(0xFFFFFF)
GUICtrlSetDefBkColor(0x000000)
$cEdit = GUICtrlCreateEdit("dir",20,20,260,260,BitOR($ES_WANTRETURN, $WS_VSCROLL, $WS_HSCROLL, $ES_AUTOVSCROLL, $ES_AUTOHSCROLL))
GUICtrlSetResizing(-1, $GUI_DOCKTOP + $GUI_DOCKBOTTOM + $GUI_DOCKLEFT + $GUI_DOCKRIGHT)
GUISetState(@SW_SHOW,$hWindow)

GUIRegisterMsg($WM_GETMINMAXINFO,"MY_WM_GETMINMAXINFO")

While 1
$smsg = GUIGetMsg()
If $smsg = -3 Then Exit
If _IsPressed("0D", $hdll) And WinActive($stitle) Then
$sText = _GUICtrlEdit_GetLine($cEdit,_GUICtrlEdit_GetLineCount($cEdit)-2)
$hDos = Run(@ComSpec & " /c " & $sText, @SystemDir, @SW_HIDE,$STDERR_MERGED)
Local $sRead="",$sTmp=""
While 1
$sTmp = StdoutRead($hDos)
If @error Then ExitLoop
$sRead &= $sTmp
WEnd
If $sRead <> "" Then
$sOld = GUICtrlRead($cEdit)
GUICtrlSetData($cEdit,$sOld & $sRead)
_GUICtrlEdit_Scroll($cEdit,$SB_SCROLLCARET )
Else
_GUICtrlEdit_Undo($cEdit)
EndIf
EndIf
WEnd

Func MY_WM_GETMINMAXINFO($hWnd, $msg, $wParam, $lParam)
$minmaxinfo = DllStructCreate("int;int;int;int;int;int;int;int;int;int", $lParam)
DllStructSetData($minmaxinfo, 7, $iBreite_Min) ; min X
DllStructSetData($minmaxinfo, 8, $iHoehe_Min) ; min Y
DllStructSetData($minmaxinfo, 9, $iBreite_Max) ; max X
DllStructSetData($minmaxinfo, 10, $iHoehe_Max) ; max Y
Return 0
EndFunc ;==>MY_WM_GETMINMAXINFO