//menuのtop
var offsettop = 0;
//動き出す位置
var movePoint = 240;
//スピード
var sp = 10;
var navID = "mainLeft";
var oldY;
function mv()
{
if(document.all)
{
	if (typeof document.body.style.maxHeight != "undefined") 
	{
		nowY = document.documentElement.scrollTop;
		} else {
		nowY = document.body.scrollTop
		} 
/*nowY = document.body.scrollTop;
nowY = document.body.scrollTop + document.documentElement.scrollTop;*/

}
else
{
nowY = self.pageYOffset;
}
if(nowY != oldY)
{
if(nowY >= movePoint)
{
objY = nowY + (offsettop - movePoint);
bytefx.move(document.getElementById(navID), {x:0, y:objY}, sp);
}
else
{
objY = offsettop;
bytefx.move(document.getElementById(navID), {x:0, y:objY}, sp);
}
oldY = nowY;
}
}
function evt_init() {
	setInterval('mv()',100);
	}

//リスナー
var dom = new Object();
dom.event = new Object();

dom.event.addEventListener = function(elm, type, func, useCapture) {
  if(! elm) { return false; }
  if(! useCapture) {
    useCapture = false;
  }
  if(elm.addEventListener) {
    elm.addEventListener(type, func, false);
  } else if(elm.attachEvent) {
    elm.attachEvent('on'+type, func);
  } else {
    return false;
  }
  return true;
};

dom.event.removeEventListener = function(elm, type, func, useCapture) {
  if(! elm) { return false; }
  if(! useCapture) {
    useCapture = false;
  }
  if(elm.removeEventListener) {
    box.removeEventListener(type, func, false);
  } else if(elm.detachEvent) {
    elm.detachEvent('on'+type, func);
  } else {
    return false;
  }
  return true;
};

dom.event.target = function(evt) {
  if(evt && evt.target) {
    if(evt.target.nodeType == 3) {
      return evt.target.parentNode;
    } else {
      return evt.target;
    }
  } else if(window.event && window.event.srcElement) {
    return window.event.srcElement;
  } else {
    return null;
  }
};

dom.event.preventDefault = function(evt) {
  if(evt && evt.preventDefault) {
    evt.preventDefault();
    evt.currentTarget['on'+evt.type] = function() {return false;};
  } else if(window.event) {
    window.event.returnValue = false;
  }
};

dom.event.stopPropagation = function(evt) {
  if(evt && evt.stopPropagation) {
    evt.stopPropagation();
  } else if(window.event) {
    window.event.cancelBubble = true;
  }
};

dom.event.dispatchEvent = function(elm, evttype) {
  if(elm.dispatchEvent) {
    var evt = document.createEvent('MouseEvents');
    evt.initEvent(evttype, true, true);
    elm.dispatchEvent(evt);
  } else if(window.event) {
    var evt = document.createEventObject();
    evt.button = 1;
    elm.fireEvent('on'+evttype, evt);
  }
}

dom.event.addEventListener(window, 'load', evt_init);