lastClickX = 0;
lastClickY = 0;
function mouseDown(ev,type){
	ev           = ev || window.event;
	var mousePos = mouseCoords(ev);
	lastClickX = mousePos.x;
	lastClickY = mousePos.y;
}

function mouseCoords(ev){
	if(ev.pageX || ev.pageY){
		return {x:ev.pageX, y:ev.pageY};
	}
	return {
		x:ev.clientX + document.body.scrollLeft - document.body.clientLeft,
		y:ev.clientY + document.body.scrollTop  - document.body.clientTop
	};
}

document.onmousedown = mouseDown;