// preload nav button mouseover images and set up javascript handling for them, if possible
if (document.images) {

  // set up highlighted and non-highlighted images for navigation buttons
  image1on = new Image(); image1on.src = "/structure/buttons/news2.gif";
  image1off = new Image(); image1off.src = "/structure/buttons/news.gif";
  image2on = new Image(); image2on.src = "/structure/buttons/meetfrank2.gif";
  image2off = new Image(); image2off.src = "/structure/buttons/meetfrank.gif";
  image3on = new Image(); image3on.src = "/structure/buttons/projects2.gif";
  image3off = new Image(); image3off.src = "/structure/buttons/projects.gif";
  image4on = new Image(); image4on.src = "/structure/buttons/calendar2.gif";
  image4off = new Image(); image4off.src = "/structure/buttons/calendar.gif";
  image5on = new Image(); image5on.src = "/structure/buttons/music2.gif";
  image5off = new Image(); image5off.src = "/structure/buttons/music.gif";
  image6on = new Image(); image6on.src = "/structure/buttons/search2.gif";
  image6off = new Image(); image6off.src = "/structure/buttons/search.gif";
  image7on = new Image(); image7on.src = "/structure/buttons/contact2.gif";
  image7off = new Image(); image7off.src = "/structure/buttons/contact.gif";
  image8on = new Image(); image8on.src = "/structure/buttons/community2.gif";
  image8off = new Image(); image8off.src = "/structure/buttons/community.gif";

  // determine which of the above to use for the active site section
  use_imageon = new Image(); use_imageoff = new Image();
  if (use_image == "image1") { use_imageon = image1on; use_imageoff = image1off; }
  if (use_image == "image2") { use_imageon = image2on; use_imageoff = image2off; }
  if (use_image == "image3") { use_imageon = image3on; use_imageoff = image3off; }
  if (use_image == "image4") { use_imageon = image4on; use_imageoff = image4off; }
  if (use_image == "image5") { use_imageon = image5on; use_imageoff = image5off; }
  if (use_image == "image6") { use_imageon = image6on; use_imageoff = image6off; }
  if (use_image == "image7") { use_imageon = image7on; use_imageoff = image7off; }

  // set up javascript switches for each button

  var switch1 = document.getElementById('switch1');
  if (switch1 && use_image != "image1") {
    switch1.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image1.src = image1on.src; }
    switch1.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image1.src = image1off.src; }
  }

  var switch2 = document.getElementById('switch2');
  if (switch2 && use_image != "image2") {
    switch2.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image2.src = image2on.src; }
    switch2.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image2.src = image2off.src; }
  }

  var switch3 = document.getElementById('switch3');
  if (switch3 && use_image != "image3") {
    switch3.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image3.src = image3on.src; }
    switch3.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image3.src = image3off.src; }
  }

  var switch4 = document.getElementById('switch4');
  if (switch4 && use_image != "image4") {
    switch4.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image4.src = image4on.src; }
    switch4.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image4.src = image4off.src; }
  }

  var switch5 = document.getElementById('switch5');
  if (switch5 && use_image != "image5") {
    switch5.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image5.src = image5on.src; }
    switch5.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image5.src = image5off.src; }
  }

  var switch6 = document.getElementById('switch6');
  if (switch6 && use_image != "image6") {
    switch6.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image6.src = image6on.src; }
    switch6.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image6.src = image6off.src; }
  }

  var switch7 = document.getElementById('switch7');
  if (switch7 && use_image != "image7") {
    switch7.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image7.src = image7on.src; }
    switch7.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image7.src = image7off.src; }
  }

  var switch8 = document.getElementById('switch8');
  if (switch8 && use_image != "image8") {
    switch8.onmouseover = function() { document.images[use_image].src = use_imageoff.src; document.images.image8.src = image8on.src; }
    switch8.onmouseout = function() { document.images[use_image].src = use_imageon.src; document.images.image8.src = image8off.src; }
  }

}