if (document.images)
   {
     pic1on= new Image(50,14);
     pic1on.src="/skin/images/overknop-home.gif";  
     pic2on= new Image(50,14);
     pic2on.src="/skin/images/overknop-terug.gif"; 
     pic3on= new Image(50,14);
     pic3on.src="/skin/images/overknop-vraag.gif"; 
     pic4on= new Image(50,14);
     pic4on.src="/skin/images/overknop-email.gif"; 
 


     pic1off= new Image(50,14);
     pic1off.src="/skin/images/knop-home.gif";
     pic2off= new Image(50,14);
     pic2off.src="/skin/images/knop-terug.gif";
     pic3off= new Image(50,14);
     pic3off.src="/skin/images/knop-vraag.gif";
     pic4off= new Image(50,14);
     pic4off.src="/skin/images/knop-email.gif";

   }

function lightup(imgName)
 {
   if (document.images)
    {
      imgOn=eval(imgName + "on.src");
      document[imgName].src= imgOn;
    }
 }

function turnoff(imgName)
 {
   if (document.images)
    {
      imgOff=eval(imgName + "off.src");
      document[imgName].src= imgOff;
    }
 }