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onmousemove event
function mymove(e)
{
var event=new MouseEvent(e);
    x = 20;
    y = 10;

    document.getElementById('mye').style.left = event.pageX + x+'px' ;
    document.getElementById('mye').style.top = event.pageY - y+'px';


    }

#mye {
    height: 25px;
    width: 250px;
    position: absolute;
    background: #ddd;
}

<div id="mye">Content</div>

var mymove = function (e) {
    var x = 20,
        y = 10,
        mye = document.getElementById('mye');

    mye.style.left = (parseInt(e.clientX) + x) + 'px';
    mye.style.top = (parseInt(e.clientY) - y) + 'px';
};

// Don't forget to add this in an onload or ondomready.
document.getElementById('mye').onmousemove = mymove;

window.onmousemove = mymove;