if (document.images)
   {
     pic1on= new Image(36,38);
     pic1on.src="images/overknop-home.gif";  
     pic2on= new Image(36,38);
     pic2on.src="images/overknop-contact.gif"; 
     pic3on= new Image(36,41);
     pic3on.src="images/overknop-sitemap.gif"; 
     pic4on= new Image(146,23);
     pic4on.src="images/overknop-tips.gif"; 
     pic5on= new Image(147,23);
     pic5on.src="images/overknop-feestlocaties.gif";
     pic6on= new Image(147,23);
     pic6on.src="images/overknop-feestbedrijven.gif"; 
     pic7on= new Image(147,23);
     pic7on.src="images/overknop-ervaringen.gif"; 
     pic8on= new Image(147,23);
     pic8on.src="images/overknop-linkpartners.gif";

     pic1off= new Image(36,38);
     pic1off.src="images/knop-home.gif";
     pic2off= new Image(36,38);
     pic2off.src="images/knop-contact.gif";
     pic3off= new Image(36,41);
     pic3off.src="images/knop-sitemap.gif";
     pic4off= new Image(146,23);
     pic4off.src="images/knop-tips.gif";
     pic5off= new Image(147,23);
     pic5off.src="images/knop-feestlocaties.gif";
     pic6off= new Image(147,23);
     pic6off.src="images/knop-feestbedrijven.gif";
     pic7off= new Image(147,23);
     pic7off.src="images/knop-ervaringen.gif";
     pic8off= new Image(147,23);
     pic8off.src="images/knop-linkpartners.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;
    }
 }