if (document.images) {
  var navGalleryOff = new Image();
  navGalleryOff.src = "img/navGalleryOff.gif";
  var navGalleryOn = new Image();
  navGalleryOn.src = "img/navGalleryOn.gif";

  var navArtistStatementOff = new Image();
  navArtistStatementOff.src = "img/navArtistStatementOff.gif";
  var navArtistStatementOn = new Image();
  navArtistStatementOn.src = "img/navArtistStatementOn.gif";

  var navBioOff = new Image();
  navBioOff.src = "img/navBioOff.gif";
  var navBioOn = new Image();
  navBioOn.src = "img/navBioOn.gif";

  var navExhibitionOff = new Image();
  navExhibitionOff.src = "img/navExhibitionOff.gif";
  var navExhibitionOn = new Image();
  navExhibitionOn.src = "img/navExhibitionOn.gif";

  var navContactOff = new Image();
  navContactOff.src = "img/navContactOff.gif";
  var navContactOn = new Image();
  navContactOn.src = "img/navContactOn.gif";

}

function act(imgName) {
  if (document.images) 
    document.images[imgName].src = eval(imgName + "On.src");
}

function inact(imgName) {
  if (document.images)
    document.images[imgName].src = eval(imgName + "Off.src");
}