function imgMenu(imgName,swapType) {
  document[imgName].src = "images/buttons/"+imgName+swapType+".gif";
}


function changeVisibility(onoff,menuname){
  if (onoff==0){
    document.getElementById(menuname).style.visibility="hidden";
    document.getElementById(menuname).style.position="absolute";
  }
  if (onoff==1){
    document.getElementById(menuname).style.visibility="visible";
    document.getElementById(menuname).style.position="static";
  }
}

function swapImage(onoff, menuname){
  changeVisibility(onoff, menuname);
  changeVisibility(1-onoff, "defaultpic");
}