function resize_img(img, max_width, max_height)
{
	var oimg = new Image();
	oimg.src = img.src;
	var ww = oimg.width;;
	var hh = oimg.height;
	var rate_w = max_width / ww;
	var rate_h = max_height / ww;
	var rate = Math.min(1, rate_w, rate_w);
	img.width = rate * ww;
	img.height = rate * hh;
	//
	img.style.display = "";
}
function set_div_position_by_mouse(event, div_name, offset_x, offset_y)
{
	var div = document.getElementById(div_name);
	if(div.style.display == "block")
	{
		offset_x = offset_x == null ? 0 : offset_x;
		offset_y = offset_y == null ? 0 : offset_y;
		div.style.left = event.clientX + document.documentElement.scrollLeft + offset_x + "px";
		div.style.top = event.clientY + document.documentElement.scrollTop + offset_y + "px";
	}
}