function showhide(id){
  if(document.getElementById){
    if(document.getElementById(id).style.display == "block"){
      document.getElementById(id).style.display = "none";
    }else{
      document.getElementById("tab").style.display = "none";
	  document.getElementById("toff").style.display = "none";
      document.getElementById(id).style.display = "block";
    }
  }
}