Discuz论坛的阴影二级下滑菜单

答案：<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>showmenu下拉菜单兼容版 </title>
<script language="JavaScript"> 
<!--
var userAgent = navigator.userAgent.toLowerCase();
var is_opera = userAgent.indexOf('opera') != -1 && opera.version();
var is_ie = (userAgent.indexOf('msie') != -1 && !is_opera) && userAgent.substr(userAgent.indexOf('msie') + 5, 3);
function $(id) {return document.getElementById(id);}
function isUndefined(variable) {return typeof variable == 'undefined' ? true : false;}
function doane(event) {
	e = event ? event : window.event;
	if(is_ie) {
		e.returnValue = false;
		e.cancelBubble = true;
	} else if(e) {
		e.stopPropagation();
		e.preventDefault();
	}
}
 
var jsmenu = new Array();
var ctrlobjclassName;
jsmenu['active'] = new Array();
jsmenu['timer'] = new Array();
jsmenu['iframe'] = new Array();
 
function initCtrl(ctrlobj, click, duration, timeout, layer) {
	if(ctrlobj && !ctrlobj.initialized) {
		ctrlobj.initialized = true;
		ctrlobj.unselectable = true;
 
		ctrlobj.outfunc = typeof ctrlobj.onmouseout == 'function' ? ctrlobj.onmouseout : null;
		ctrlobj.onmouseout = function() {
			if(this.outfunc) this.outfunc();
			if(duration < 3) jsmenu['timer'][ctrlobj.id] = setTimeout('hideMenu(' + layer + ')', timeout);
		}
 
		ctrlobj.overfunc = typeof ctrlobj.onmouseover == 'function' ? ctrlobj.onmouseover : null;
		ctrlobj.onmouseover = function(e) {
			doane(e);
			if(this.overfunc) this.overfunc();
			if(click) {
				clearTimeout(jsmenu['timer'][this.id]);
			} else {
				for(var id in jsmenu['timer']) {
					if(jsmenu['timer'][id]) clearTimeout(jsmenu['timer'][id]);
				}
			}
		}
	}
}
 
function initMenu(ctrlid, menuobj, duration, timeout, layer, drag) {
	if(menuobj && !menuobj.initialized) {
		menuobj.initialized = true;
		menuobj.ctrlkey = ctrlid;
		menuobj.onclick = ebygum;
		menuobj.style.position = 'absolute';
		if(duration < 3) {
			if(duration > 1) {
				menuobj.onmouseover = function() {
					clearTimeout(jsmenu['timer'][ctrlid]);
				}
			}
			if(duration != 1) {
				menuobj.onmouseout = function() {
					jsmenu['timer'][ctrlid] = setTimeout('hideMenu(' + layer + ')', timeout);
				}
			}
		}
		menuobj.style.zIndex = 50;
		if(is_ie) {
			menuobj.style.filter += "progid:DXImageTransform.Microsoft.shadow(direction=135,color=#CCCCCC,strength=2)";
		}
		if(drag) {
			menuobj.onmousedown = function(event) {try{menudrag(menuobj, event, 1);}catch(e){}};
			menuobj.onmousemove = function(event) {try{menudrag(menuobj, event, 2);}catch(e){}};
			menuobj.onmouseup = function(event) {try{menudrag(menuobj, event, 3);}catch(e){}};
		}
	}
}
 
var menudragstart = new Array();
function menudrag(menuobj, e, op) {
	if(op == 1) {
		if(in_array(is_ie ? event.srcElement.tagName : e.target.tagName, ['TEXTAREA', 'INPUT', 'BUTTON', 'SELECT'])) {
			return;
		}
		menudragstart = is_ie ? [event.clientX, event.clientY] : [e.clientX, e.clientY];
		menudragstart[2] = parseInt(menuobj.style.left);
		menudragstart[3] = parseInt(menuobj.style.top);
		doane(e);
	} else if(op == 2 && menudragstart[0]) {
		var menudragnow = is_ie ? [event.clientX, event.clientY] : [e.clientX, e.clientY];
		menuobj.style.left = (menudragstart[2] + menudragnow[0] - menudragstart[0]) + 'px';
		menuobj.style.top = (menudragstart[3] + menudragnow[1] - menudragstart[1]) + 'px';
		doane(e);
	} else if(op == 3) {
		menudragstart = [];
		doane(e);
	}
}
 
function showMenu(ctrlid, click, offset, duration, timeout, layer, showid, maxh, drag) {
	var ctrlobj = $(ctrlid);
	if(!ctrlobj) return;
	if(isUndefined(click)) click = false;
	if(isUndefined(offset)) offset = 0;
	if(isUndefined(duration)) duration = 2;
	if(isUndefined(timeout)) timeout = 500;
	if(isUndefined(layer)) layer = 0;
	if(isUndefined(showid)) showid = ctrlid;
	var showobj = $(showid);
	var menuobj = $(showid + '_menu');
	if(!showobj|| !menuobj) return;
	if(isUndefined(maxh)) maxh = 400;
	if(isUndefined(drag)) drag = false;
 
	if(click && jsmenu['active'][layer] == menuobj) {
		hideMenu(layer);
		return;
	} else {
		hideMenu(layer);
	}
 
	var len = jsmenu['timer'].length;
	if(len > 0) {
		for(var i=0; i<len; i++) {
			if(jsmenu['timer'][i]) clearTimeout(jsmenu['timer'][i]);
		}
	}
 
	initCtrl(ctrlobj, click, duration, timeout, layer);
	ctrlobjclassName = ctrlobj.className;
	ctrlobj.className += ' hover';
	initMenu(ctrlid, menuobj, duration, timeout, layer, drag);
 
	menuobj.style.display = '';
	if(!is_opera) {
		menuobj.style.clip = 'rect(auto, auto, auto, auto)';
	}
 
	setMenuPosition(showid, offset);
 
	if(is_ie && is_ie < 7) {
		if(!jsmenu['iframe'][layer]) {
			var iframe = document.createElement('iframe');
			iframe.style.display = 'none';
			iframe.style.position = 'absolute';
			iframe.style.filter = 'progid:DXImageTransform.Microsoft.Alpha(style=0,opacity=0)';
			$('append_parent') ? $('append_parent').appendChild(iframe) : menuobj.parentNode.appendChild(iframe);
			jsmenu['iframe'][layer] = iframe;
		}
		jsmenu['iframe'][layer].style.top = menuobj.style.top;
		jsmenu['iframe'][layer].style.left = menuobj.style.left;
		jsmenu['iframe'][layer].style.width = menuobj.w;
		jsmenu['iframe'][layer].style.height = menuobj.h;
		jsmenu['iframe'][layer].style.display = 'block';
	}
 
	if(maxh && menuobj.scrollHeight > maxh) {
		menuobj.style.height = maxh + 'px';
		if(is_opera) {
			menuobj.style.overflow = 'auto';
		} else {
			menuobj.style.overflowY = 'auto';
		}
	}
 
	if(!duration) {
		setTimeout('hideMenu(' + layer + ')', timeout);
	}
 
	jsmenu['active'][layer] = menuobj;
}
 
function setMenuPosition(showid, offset) {
	var showobj = $(showid);
	var menuobj = $(showid + '_menu');
	if(isUndefined(offset)) offset = 0;
	if(showobj) {
		showobj.pos = fetchOffset(showobj);
		showobj.X = showobj.pos['left'];
		showobj.Y = showobj.pos['top'];
		showobj.w = showobj.offsetWidth;
		showobj.h = showobj.offsetHeight;
		menuobj.w = menuobj.offsetWidth;
		menuobj.h = menuobj.offsetHeight;
		if(offset < 3) {
			menuobj.style.left = (showobj.X + menuobj.w > document.body.clientWidth) && (showobj.X + showobj.w - menuobj.w >= 0) ? showobj.X + showobj.w - menuobj.w + 'px' : showobj.X + 'px';
			menuobj.style.top = offset == 1 ? showobj.Y + 'px' : (offset == 2 || ((showobj.Y + showobj.h + menuobj.h > document.documentElement.scrollTop + document.documentElement.clientHeight) && (showobj.Y - menuobj.h >= 0)) ? (showobj.Y - menuobj.h) + 'px' : showobj.Y + showobj.h + 'px');
		} else if(offset == 3) {
			menuobj.style.left = (document.body.clientWidth - menuobj.clientWidth) / 2 + document.body.scrollLeft + 'px';
			menuobj.style.top = (document.body.clientHeight - menuobj.clientHeight) / 2 + document.body.scrollTop + 'px';
		}
		if(menuobj.style.clip && !is_opera) {
			menuobj.style.clip = 'rect(auto, auto, auto, auto)';
		}
	}
}
 
function hideMenu(layer) {
	if(isUndefined(layer)) layer = 0;
	if(jsmenu['active'][layer]) {
		try {
			$(jsmenu['active'][layer].ctrlkey).className = ctrlobjclassName;
		} catch(e) {}
		clearTimeout(jsmenu['timer'][jsmenu['active'][layer].ctrlkey]);
		jsmenu['active'][layer].style.display = 'none';
		if(is_ie && is_ie < 7 && jsmenu['iframe'][layer]) {
			jsmenu['iframe'][layer].style.display = 'none';
		}
		jsmenu['active'][layer] = null;
	}
}
 
function fetchOffset(obj) {
	var left_offset = obj.offsetLeft;
	var top_offset = obj.offsetTop;
	while((obj = obj.offsetParent) != null) {
		left_offset += obj.offsetLeft;
		top_offset += obj.offsetTop;
	}
	return { 'left' : left_offset, 'top' : top_offset };
}
 
function ebygum(eventobj) {
	if(!eventobj || is_ie) {
		w
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