function filter()
{
	//var categories = '';
	//var subject = document.getElementById('cat');
 	//categories = subject;
 	// neue URL mit Variable 'categories' zusammen setzen
	//window.location = document.getElementById('newsfilterform').action + '?no_cache=1&cat=' + categories;


  var i,categories="";
  var seite = document.location.href;

  if (seite.indexOf("?") > 0) {
    seite = seite.substr(0,seite.indexOf("?"));
  }


  for (i = 0; i < document.filterform.cat.length; i++) {
    if (document.filterform.cat[i].checked)
      categories = categories + document.filterform.cat[i].value+",";
  }

  categories = categories.substr(0, categories.length -1);
  window.location = seite + '?no_cache=1&tx_ttnews[cat]=' + categories;

}