function activate(imgName) {
         if (document.images) {
            document[imgName].src = eval(imgName + "_hi.src");
         }
      }
	    
      function deactivate(imgName) {
         if (document.images) {
            document[imgName].src = eval(imgName + ".src");
         }
      }

      if (document.images) {
         img_nav1 = new Image();
         img_nav1.src = "img/home_in.gif";
         img_nav1_hi = new Image ();
         img_nav1_hi.src = "img/home_act.gif";
         img_nav2 = new Image();
         img_nav2.src = "img/kurse_in.gif";
         img_nav2_hi = new Image ();
         img_nav2_hi.src = "img/kurse_act.gif";
         img_nav3 = new Image();
         img_nav3.src = "img/berichte_in.gif";
         img_nav3_hi = new Image ();
         img_nav3_hi.src = "img/berichte_act.gif";
      }// end if