Cmq, così, per non aver nulla da fare… ti ho semplificato di brutto quello che stai già facendo…

codice:
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Draggable objects</title>
<script type="text/javascript">
var bMouseUp = true, oDragging, nMouseX, nMouseY, nStartX, nStartY, nZFocus = 100 /* the highest z-Index present in your page plus 1 */;

function dragDown(oPssEvt1) {
	var oMsEvent1 = oPssEvt1 || /* IE */ window.event;
	oDragging = oMsEvent1.target;
	if (oDragging.className !== "draggable") { return; }
	bMouseUp = false;
	nStartX = nStartY = 0;
	for (var iOffPar = oDragging; iOffPar; iOffPar = iOffPar.offsetParent) {
		nStartX += iOffPar.offsetLeft;
		nStartY += iOffPar.offsetTop;
	}
	nMouseX = oMsEvent1.clientX;
	nMouseY = oMsEvent1.clientY;
	oDragging.style.zIndex = nZFocus++;
	return false;
}

function dragMove(oPssEvt2) {
	if (bMouseUp) { return; }
	var oMsEvent2 = oPssEvt2 || /* IE */ window.event;
	oDragging.style.left = String(nStartX + oMsEvent2.clientX - nMouseX) + "px";
	oDragging.style.top = String(nStartY + oMsEvent2.clientY - nMouseY) + "px";
}

function dragUp() { bMouseUp = true; }

function keyListener(oPssEvt3) {
	var oKeyEvt1 = oPssEvt3 || /* IE */ window.event;
	if (oKeyEvt1.ctrlKey && oKeyEvt1.charCode === 109) { // ctrl + m
		document.getElementById("votazione").style.display = "block";
	}
}

document.onmousedown = dragDown;
document.onmousemove = dragMove;
document.onmouseup = dragUp;
document.onkeypress = keyListener;
</script>
<style type="text/css">
.draggable {
	position: fixed;
	left: 0;
	top: 0;
	width: auto;
	height: auto;
	cursor: move;
}

#votazione {
	width: 300px;
	height: 200px;
	left: 200px;
	top: 200px;
	background-color: #00ff00;
	display: none;
}
</style>
</head>

<body>


Premi ctrl + m !!</p>
<div class="draggable" id="votazione">Hello world!</div>
</body>
</html>