if (document.images) {
    var first_off = new Image();
    var first_on = new Image();

    var second_off = new Image();
    var second_on = new Image();

    var third_off = new Image();
    var third_on = new Image();

    var fourth_off = new Image();
    var fourth_on = new Image();

    var fifth_off = new Image();
    var fifth_on = new Image();
  }


  function loadImages() {
    if (document.images) {
      first_off.src = "./images/button_1_ro.gif";
      first_on.src = "./images/button_1_ro_on.gif";

      second_off.src = "./images/button_2_ro.gif";
      second_on.src = "./images/button_2_ro_on.gif";

      third_off.src = "./images/button_3_ro.gif";
      third_on.src = "./images/button_3_ro_on.gif";

      fourth_off.src = "./images/button_4_ro.gif";
      fourth_on.src = "./images/button_4_ro_on.gif";

      fifth_off.src = "./images/button_5_ro.gif";
      fifth_on.src = "./images/button_5_ro_on.gif";
    }
  }

  function activate(imgName) {
    if (document.images) {
      if ( eval(imgName + "_on.complete") ) {
        document.images[imgName].src = eval(imgName + "_on.src");
      }
    }
  }

  function deactivate(imgName) {
    if (document.images) {
      if ( eval(imgName + "_off.complete") ) {
        document.images[imgName].src = eval(imgName + "_off.src");
      }
    }
  }