var user_agent = navigator.userAgent.toLowerCase();
var app_version = navigator.appVersion.toLowerCase();

var is_ie = ((user_agent.indexOf("msie") != -1) && (user_agent.indexOf("opera") == -1));
var is_gecko = (user_agent.indexOf('gecko') != -1);
var is_opera = (user_agent.indexOf("opera") != -1);
var is_ie8 = (app_version.indexOf("msie 8.0") != -1);

function getPosition(targetEle) 
{
    var pos = new function(){ this.x = 0; this.y = 0; }
    while( targetEle ){
	pos.x += targetEle.offsetLeft;
	pos.y += targetEle.offsetTop;
	targetEle = targetEle.offsetParent;
    }
    return pos;
}

function moveMPU()
{
    $('mpuEntity').style.position = 'absolute';
    var slot_pos = getPosition($('mpuSlot'));
    var tmp = document.getElementsByClassName('global-center');
    var gcenter = tmp[0];
    var gcenter_pos = getPosition(gcenter);

    var ie_offset = 0;
    if(is_ie8 || is_opera) ie_offset += 13; // IE8はさらに13px補正する。global-center:border幅

    $('mpuEntity').style.top = (slot_pos.y - ie_offset) + 'px';
    $('mpuEntity').style.left = (slot_pos.x - gcenter_pos.x - ie_offset) + 'px';
}

Event.observe(window, 'load', function(){
    moveMPU();
});