if(VZT.Easing === undefined) {
	VZT.Easing = {
		Bounce:{
			easeOut:function(t,b,c,d) {
				if ((t/=d) < (1/2.75)) {
					return c*(7.5625*t*t) + b;
				} else if (t < (2/2.75)) {
					return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;
				} else if (t < (2.5/2.75)) {
					return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;
				} else {
					return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;
				}
			},
			easeIn:function(t,b,c,d) {
				return c - Easing.Bounce.easeOut(d-t, 0, c, d) + b;
			},
			easeInOut:function(t,b,c,d) {
				if (t < d/2) return Easing.Bounce.easeIn(t*2, 0, c, d) * .5 + b;
				else return Easing.Bounce.easeOut(t*2-d, 0, c, d) * .5 + c*.5 + b;
			}
		},
		Elastic:{
			easeIn:function(t,b,c,d,a,p) {
				a = a || null;p=p||null;
				if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
				if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
				else var s = p/(2*Math.PI) * Math.asin (c/a);
				return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
			},
			easeOut:function(t,b,c,d,a,p) {
				a = a || null;p=p||null;
				if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
				if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
				else var s = p/(2*Math.PI) * Math.asin (c/a);
				return (a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b);
			},
			easeInOut:function(t,b,c,d,a,p) {
				a = a || null;p=p||null;
				if (t==0) return b;  if ((t/=d/2)==2) return b+c;  if (!p) p=d*(.3*1.5);
				if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
				else var s = p/(2*Math.PI) * Math.asin (c/a);
				if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
				return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
			}
		},
		Expo:{
			easeIn:function(t,b,c,d) {
				return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;
			},
			easeOut:function(t,b,c,d) {
				return (t==d) ? b+c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
			},
			easeInOut:function(t,b,c,d) {
				if (t==0) return b;
				if (t==d) return b+c;
				if ((t/=d/2) < 1) return c/2 * Math.pow(2, 10 * (t - 1)) + b;
				return c/2 * (-Math.pow(2, -10 * --t) + 2) + b;
			}   
		},
		Sine:{
			easeIn:function(t,b,c,d) {
				return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
			},
			easeOut:function(t,b,c,d) {
				return c * Math.sin(t/d * (Math.PI/2)) + b;
			},
			easeInOut:function(t,b,c,d) {
				return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
			}
		},
		Linear: {
			easeIn:function(t,b,c,d) {
			
				return t * ((c-b) / d);
			},
			easeOut:function(t,b,c,d) {
				return t * ((c-b) / d);
			}
		}
		
	};
} else {
	// was added in this version of the lib
	VZT.Easing.Linear = {
		easeIn:function(t,b,c,d) {	
			return t * ((c-b) / d);
		},
		easeOut:function(t,b,c,d) {
			return t * ((c-b) / d);
		}
	}
} 

if(VZT.Tween === undefined) {
	VZT.Tween = function(el,prop,begin,finish,duration,type,onComplete) {
		this.el = el;
		this.prop = prop;
		this.begin = begin; //parseInt(this.el.style[prop],10);
		this.finish = finish;
		this.duration = duration;
		this.change = this.finish - this.begin;
		this.type = type;
		this.onComplete = onComplete || (function() {});

	};
	VZT.Tween.prototype = {
		//begin:0,
		finish:0,
		duration:200,
		change:0,
		time:0,
		start:function() {
		  var me = this;
		  this.timer = setInterval(function() {
			me.step();
		  },24);
		},
		step:function() {
		  var prefix = "";
		  if(this.prop !== "opacity")
			prefix = "px";
		  this.el.style[this.prop] = this.type(this.time++, this.begin, this.change, this.duration) + prefix;
			if (this.time > this.duration) {
				this.stop();
				this.onComplete();
				
			}
		},
		stop:function() {
			clearInterval(this.timer);
		}
	};
}