Запрет на переключение раскладки - VB

procedure TForm1.FormCreate(Sender: TObject);
begin
 Application.OnMessage := MsgHandler;
end;
 
procedure TForm1.MsgHandler(var Msg: TMsg; var Handled: Boolean);
begin
 if Msg.message = WM_INPUTLANGCHANGEREQUEST then 
  if CheckBox1.checked then 
   Handled := true;
end;

Public Const GWL_WNDPROC = (-4)
Public Const WM_INPUTLANGCHANGEREQUEST = &H50
Public Const WM_INPUTLANGCHANGE = &H51
Public lpPrevWndProc As Long
 
Declare Function CallWindowProc Lib "USER32" Alias _
         "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd As _
         Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As _
         Long) As Long
 
Public Declare Function SetWindowLong Lib "USER32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
 
Public Sub Hook()
  lpPrevWndProc = SetWindowLong(frmMain.hWnd, GWL_WNDPROC, AddressOf WindowProc)
  Debug.Print lpPrevWndProc
End Sub
 
Public Sub Unhook()
  Dim temp As Long
  temp = SetWindowLong(frmMain.hWnd, GWL_WNDPROC, lpPrevWndProc)
End Sub
 
Function WindowProc(ByVal hw As Long, ByVal uMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
  Select Case uMsg
  Case WM_INPUTLANGCHANGEREQUEST
    MsgBox "ГЉГ«Г*ГўГ*."
  Case WM_INPUTLANGCHANGE
    MsgBox "ГЉГ«Г*ГўГ*!"
  Case 307
    WindowProc = CallWindowProc(lpPrevWndProc, hw, uMsg, wParam, lParam)
  Case Else
    frmMain.rtf(1).text = frmMain.rtf(1).text & uMsg
    WindowProc = CallWindowProc(lpPrevWndProc, hw, uMsg, wParam, lParam)
  End Select
End Function