function Status = zReleaseWindow(FileName)
% zReleaseWindow - Release locked window.
%
% Usage : Status = zReleaseWindow(FileName)
% When ZEMAX calls the client to update or change the settings used by the client function, the menu bar is
% grayed out on the window to prevent multiple updates or setting changes from being requested simultaneously.
% Normally, when the client code sends the MakeTextWindow or MakeGraphicWindow, the menu bar is once again
% activated. However, if during an update or setting change, the new data cannot be computed, then the window
% must be released. The ReleaseWindow serves just this one simple purpose. If the user selects "Cancel" when
% changing the settings, the client code should send a ReleaseWindow item to release the lock out of the menu
% bar. If this command is not sent, the window cannot be closed, which will prevent ZEMAX from terminating
% normally. The ReleaseWindow item takes just one argument: the name of the temporary file.
% The return value is zero if no window is using the filename, or a positive integer number if the file is being used.
% A value of -998 is returned if the command times out.

% MZDDE - The ZEMAX DDE Toolbox for Matlab.
% Copyright (C) 2002-2004 Defencetek, CSIR
% Contact : dgriffith@csir.co.za
% 
% This file is part of MZDDE.
% 
%  MZDDE is free software; you can redistribute it and/or modify
%  it under the terms of the GNU General Public License as published by
%  the Free Software Foundation; either version 2 of the License, or
%  (at your option) any later version.
%
%  MZDDE is distributed in the hope that it will be useful,
%  but WITHOUT ANY WARRANTY; without even the implied warranty of
%  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
%  GNU General Public License for more details.
%
%  You should have received a copy of the GNU General Public License
%  along with MZDDE (COPYING.html); if not, write to the Free Software
%  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
%


% Copyright 2002, Defencetek, CSIR
% $Revision: 1.4 $

global ZemaxDDEChannel ZemaxDDETimeout
DDECommand = sprintf('GetVersion,%s', FileName);
Reply = ddereq(ZemaxDDEChannel, DDECommand, [1 1], ZemaxDDETimeout);
if (Reply), Status = str2num(Reply); else Status = -998; end;