function preloadImages() {
  img1 = new Image
  img1.src = "images/pubassistance_on.gif"
  img1off = new Image
  img1off.src = "images/pubassistance_off.gif"
  img2 = new Image
  img2.src = "images/adveducation_on.gif"
  img2off = new Image
  img2off.src = "images/adveducation_off.gif"
  img3 = new Image
  img3.src = "images/ecdev_on.gif"
  img3off = new Image
  img3off.src = "images/ecdev_off.gif"
  img4 = new Image
  img4.src = "images/manufacturing_on.gif"
  img4off = new Image
  img4off.src = "images/manufacturing_off.gif"
}

function swapImg(thisImg) {
  thisTarget = eval ("target" + thisImg)
  newImg = eval ("img" + thisImg)
  thisTarget.src = newImg.src
}

function restoreImg(thisImg) {
  thisTarget = eval ("target" + thisImg)
  oldImg = eval ("img" + thisImg + "off")
  thisTarget.src = oldImg.src
}