function OpenPopupFile( file_name, title, wparam, hparam )
{
  var width = eval(wparam ? wparam : 480);
  var height = eval(hparam ? hparam : 280);
  // Fenster zentrieren
  var padding = (navigator.appName == "Microsoft Internet Explorer") ? (padding = 10) : (padding = 0);
  var screenw = screen.availWidth;
  var screenh = screen.availHeight;
  var winw = (width + 15 + padding);
  var winh = (height + 15 + padding);
  var posx = (screenw / 2) - (winw / 2);
  var posy = (screenh / 2) - (winh / 2);
  var ret = window.open( file_name, "popup", 
						  "top="+posy+",left="+posx+",width="+width+",height="+height+",resizable,scrollbars=yes" );
  if( ret ) return false;
  else return true;
}