// Global Variables
    var imageLocation = "/img/";
    var buttons       = new Array();   

    function Button(buttonName, buttonOff, buttonOn) {
        this.name          = buttonName;
        this.offImage      = new Image();
        this.offImage.src  = imageLocation+buttonOff;
        this.onImage       = new Image();
        this.onImage.src   = imageLocation+buttonOn; 
    }

    function addButton(buttonName, buttonOff, buttonOn) {
        buttons[buttons.length] = new Button(buttonName, buttonOff, buttonOn);
    }

    function changeImages() {
      if (document.images) {
        for(var i=0; i<buttons.length; i++) {
          if(changeImages.arguments[0] == buttons[i].name) {
            document.images[changeImages.arguments[0]].src = eval("buttons[i]."+changeImages.arguments[1]+"Image.src");
          }
        }
      }
    }