%% Check Matlab version for use of KeyPressFcn and KeyReleaseFcn properties

% -------------------------------------------------------------------------
switch ( version('-release') )
  case { '11', '12', '13', '14', '2006a', '2006b' }
    % dont process KeyPressFcn and KeyReleaseFcn events
  otherwise
    
   % show crossline when shitf key is pressed, vertical bar when ctrl key
   % --------------------------------------------------------------------
   set( hMainFig, 'KeyPressFcn',   @keyPressFcnCallback,...
                  'KeyReleaseFcn', @keyReleaseFcnCallback);
end