var LastDiv = null;
function overlay(curobj, subobjstr, opt_position) {
	if (LastDiv) { 
		overlayclose(LastDiv); 
		LastDiv = subobjstr;
	}
	if (document.getElementById) {
		var subobj = document.getElementById(subobjstr);
		subobj.style.display = (subobj.style.display != "block") ? "block" : "none";
		var xpos = getposOffset(curobj, "left");
		var ypos = getposOffset(curobj, "top");
		if (typeof opt_position != "undefined") {
			if (opt_position.indexOf("right") != -1) xpos -= (subobj.offsetWidth - curobj.offsetWidth);
			if (opt_position.indexOf("bottom") != -1) ypos += curobj.offsetHeight;
		}
		var t = Canvas.viewportSize(window).width;
		var xmax = t - 400 - 20;
		if (xpos > xmax) xpos = xmax;
		if (xpos < 5) xpos = 5;

		subobj.style.left = xpos + "px";
		subobj.style.top = ypos + "px";
		LastDiv = subobjstr;
		return false;
	}
	return true;
}
function getposOffset(overlay, offsettype) {
	var totaloffset = (offsettype == "left") ? overlay.offsetLeft : overlay.offsetTop;
	var parentEl = overlay.offsetParent;
	while (parentEl != null) {
		totaloffset = (offsettype == "left") ? totaloffset + parentEl.offsetLeft : totaloffset + parentEl.offsetTop;
		parentEl = parentEl.offsetParent;
	}
	return totaloffset;
}
function overlayclose(subobj) {
	document.getElementById(subobj).style.display = "none";
	return false;
}