var NS4 = (document.layers) ? 1 : 0;
     var IE4 = (document.all) ? 1 : 0;

     function animation(id) {
       this.element = (NS4) ? document[id] : document.all[id].style;
       this.active = 0;
       this.timer = null;
       this.path = null;
       this.num = null;

       this.name = id + "Var";
       eval(this.name + " = this");

       this.animate = animate;
       this.step = step;
       this.show = show;
       this.hide = hide;
       this.left = left;
       this.top = top;
       this.moveTo = moveTo;
       this.slideBy = slideBy;
       this.slideTo = slideTo;
       this.circle = circle;
     }

     function pos(x, y) {
       this.x = Math.round(x);
       this.y = Math.round(y);
     }

     function show() {
       this.element.visibility = (NS4) ? "show" : "visible";
     }

     function hide() {
       this.element.visibility = (NS4) ? "hide" : "hidden";
     }

     function left() {
       return parseInt(this.element.left);
     }

     function top() {
       return parseInt(this.element.top);
     }

     function moveTo(x, y) {
       this.element.left = x;
       this.element.top = y;
     }

     function step() {
       this.moveTo(this.path[this.num].x, this.path[this.num].y);
       if (this.num >= this.path.length - 1) {
         clearInterval(this.timer);
         this.active = 0;
         if (this.statement)
           eval(this.statement);
       } else {
         this.num++;
       }
     }

     function animate(interval) {
       if (this.active) return;
       this.num = 0;
       this.active = 1;
       this.timer = setInterval(this.name + ".step()", interval);
     }

     function slideBy(dx, dy, steps, interval, statement) {
       var fx = this.left();
       var fy = this.top();
       var tx = fx + dx;
       var ty = fy + dy;
       this.slideTo(tx, ty, steps, interval, statement);
     }

     function slideTo(tx, ty, steps, interval, statement) {
       var fx = this.left();
       var fy = this.top();
       var dx = tx - fx;
       var dy = ty - fy;
       var sx = dx / steps;
       var sy = dy / steps;

       var ar = new Array();
       for (var i = 0; i < steps; i++) {
         fx += sx;
         fy += sy;
         ar[i] = new pos(fx, fy);
       }
       this.path = ar;

       this.statement = (statement) ? statement : null;
       this.animate(interval);
     }

     function circle(radius, angle0, angle1, steps, interval, statement) {
       var dangle = angle1 - angle0;
       var sangle = dangle / steps;
       var x = this.left();
       var y = this.top();
       var cx = x - radius * Math.cos(angle0 * Math.PI / 180);
       var cy = y + radius * Math.sin(angle0 * Math.PI / 180);

       var ar = new Array();
       for (var i = 0; i < steps; i++) {
         angle0 += sangle;
         x = cx + radius * Math.cos(angle0 * Math.PI / 180);
         y = cy - radius * Math.sin(angle0 * Math.PI / 180);
         ar[i] = new pos(x, y);
       }
       this.path = ar;

       this.statement = (statement) ? statement : null;
       this.animate(interval);
     }