function imgOn(imgName) {
  if (document.images) {
    document[imgName].src = eval(imgName + '_on.src');
  }
}

function imgOff(imgName) {
  if (document.images) {
    document[imgName].src = eval(imgName + '_off.src');
  }
}

if (document.images) {
  About_on = new Image();
  About_on.src = 'images/area_about_hover.gif';
  About_off = new Image();
  About_off.src = 'images/area_about.gif';
  Downloads_on = new Image();
  Downloads_on.src = 'images/area_downloads_hover.gif';
  Downloads_off = new Image();
  Downloads_off.src = 'images/area_downloads.gif';
  Community_on = new Image();
  Community_on.src = 'images/area_community_hover.gif';
  Community_off = new Image();
  Community_off.src = 'images/area_community.gif';
  Showcases_on = new Image();
  Showcases_on.src = 'images/area_showcases_hover.gif';
  Showcases_off = new Image();
  Showcases_off.src = 'images/area_showcases.gif';
}