dynObj.prototype.slideTo = function(destY,slideTime,fn,container) {
	this.slideTime = slideTime||.0001; this.fn=fn||null;
	// ok to slide along one axis only
	if (destY==null) destY=this.y;
	this.distY=this.destY-this.y; this.startY=this.y;
	this.slideStart = (new Date()).getTime();
	if (this.slideProp=="steady") this.per = 1/this.slideTime;
	else this.per = Math.PI/(2*this.slideTime);
	this.sliding=true;
	this.doSlide();
}

dynObj.prototype.slideBy = function(dy,slideTime,fn,container) {
	 var destY=this.y+dy;
	this.slideTo(destY,slideTime,fn,container);
}



// do you want your slides to be steady, accelerate or decelerate?
dynObj.prototype.slideProp="dec";	// can be "steady", "acc", or "dec"

dynObj.prototype.onSlide=function() {}
dynObj.prototype.onSlideEnd=function() {}