function addEvent(obj, type, handler) {
		if (obj.addEventListener) {
		  obj.addEventListener(type, handler, false);
		} else {
		  obj.attachEvent("on" + type, handler);
		};
	};
	
	function removeEvent(obj, type, handler) {
		if (obj.removeEventListener) {
		  obj.removeEventListener(type, handler, false);
		} else {
		  obj.detachEvent("on" + type, handler);
		}
	}
	
	function makeImg(url) {
		if (Image) {
			var x = new Image();
			x.src = 'http://' + document.domain + url;
			return x;
		}
		else {
			var x = {};
			x.src = 'http://' + document.domain + url;
		}
	}
	
	var img_contents = makeImg('/img/contents_btn.png');
	var img_active_contents = makeImg('/img/contents_active_btn.png');
	var img_about = makeImg('/img/about_btn.png');
	var img_active_about = makeImg('/img/about_active_btn.png');
	
	function getLeft(obj) {
		if (obj.offsetParent == null) {
			return obj.offsetLeft;
		}
		return obj.offsetLeft + getLeft(obj.offsetParent);
	}
	
	function getTop(obj) {
		if (obj.offsetParent == null) {
			return obj.offsetTop;
		}
		return obj.offsetTop + getTop(obj.offsetParent);
	}
	
	function getRight(obj) {
		return getLeft(obj) + obj.offsetWidth;
	}

	function getBottom(obj) {
		return getTop(obj) + obj.offsetHeight;
	}

	function hidemainmenu(evt) {
		var mmc = document.getElementById('mainmenucontainer');	
		if ((evt.target != mmc) && (evt.srcElement != mmc)) {
			var imgContents = document.getElementById('imgContents');	
			var mm = document.getElementById('mainmenu');
			removeEvent(document, 'mouseup', hidemainmenu);
			removeEvent(window, 'resize', resizemenu);
			if ((evt.target != imgContents) && (evt.srcElement != imgContents))
				mm.style.display = 'none';
		}
	}

	function resizemenu() {
		var imgContents = document.getElementById('imgContents');	
		var mm = document.getElementById('mainmenu');
		mm.style.left = getLeft(imgContents) + 'px';
	}

	function showmainmenu() {
		var imgContents = document.getElementById('imgContents');	
		var mm = document.getElementById('mainmenu');
		mm.style.top = (getBottom(imgContents) - 5) + 'px';
		mm.style.left = getLeft(imgContents) + 'px';
		mm.style.display = (mm.style.display=='block')?'none':'block';
		addEvent(document, 'mouseup', hidemainmenu);
		addEvent(window, 'resize', resizemenu);
	}
	
	function docendfunc() {
		var imgContents = document.getElementById('imgContents');	
		addEvent(imgContents, 'mouseover', function(){imgContents.src = img_active_contents.src;});
		addEvent(imgContents, 'mouseout', function(){imgContents.src = img_contents.src;});
		imgContents.parentNode.onclick = function(){this.blur(); return false;};
		addEvent(imgContents, 'click', showmainmenu);
		var imgAbout = document.getElementById('imgAbout');	
		addEvent(imgAbout, 'mouseover', function(){imgAbout.src = img_active_about.src;});
		addEvent(imgAbout, 'mouseout', function(){imgAbout.src = img_about.src;});
		var mmc = document.getElementById('mainmenucontainer');
		var menulinks = mmc.getElementsByTagName('a');
		for (var i=menulinks.length-1; i>=0; i--) {
			if (
				(menulinks[i].href == document.location.href) || 
				((menulinks[i].href + '/') == document.location.href) ||
				(menulinks[i].href == (document.location.href + '/'))
			){
				menulinks[i].className = 'mainmenu_selected';
				break;
			}
		}
	}
	
	function showhide(en) {
		var e = document.getElementById(en);
		if (e.style.display && (e.style.display == 'block')) {
			e.style.display = 'none';
		}
		else {
			e.style.display = 'block';
		}
	}
	
	function doRet() {
		window.history.go(-1);
	}