var
 divs=document.getElementsByTagName("div");
function fx_effect(n)
 {
  divs["butt"+n.toString()].style.display="none";
  divs["butt"+n.toString()+"_a"].style.display="block";
 }
function unfx_effect(n)
 {
  divs["butt"+n.toString()+"_a"].style.display="none";
  divs["butt"+n.toString()].style.display="block";
 }