function initDragDrop() {
	__dragX = 0; // cursor X
	__dragY = 0; // cursor Y
	__dragId = ""; // ID do el. a ser movido
	__dragging = false; // true se há um el. sendo movido
	document.body.onmousedown = __dragDown;
	document.body.onmousemove = __dragMove;
	document.body.onmouseup = function() { __dragging = false; };
}

function __dragMove(e) {
	if(typeof __dragging == "undefined" || !__dragging) return;
	e = e ? e : window.event;
	__dragEl.style.left = (e.clientX - __dragX)+"px";
	__dragEl.style.top = (e.clientY - __dragY)+"px";
};

function __dragDown(e) {
	e = e ? e : window.event;
	__dragEl = document.getElementById(__dragId) || null;
	var _target = document.all ? e.srcElement : e.target;

	if(!__dragEl) return;
	__dragX = e.clientX - __dragEl.offsetLeft;
	__dragY = e.clientY - __dragEl.offsetTop;
	__dragging = true;
};