if(theElement.hasClass('acitem') && theElement.is(':visible')) {
                        if($(parent).hasClass('collapsible')) {
                            $('.acitem:visible', parent).first().slideUp('normal', 
                            function() {
                                $(this).prev().removeClass('active');
                            }
                        );
                        return false;  
                    }

<ul class="menu collapsible">
		<a href="detail.php?category=01">Thema1</a>
			<ul class="acitem">
				<li><a href="detail.php?category=011">Thema1 Spezial1</a></li>
				<li><a href="detail.php?category=012">Thema1 Spezial2</a></li>				
			</ul>				
	</ul>

jQuery.fn.initMenu = function() {  
    return this.each(function(){
        var theMenu = $(this).get(0);
        $('.acitem', this).hide();
        $('li.expand > .acitem', this).show();
        $('li.expand > .acitem', this).prev().addClass('active');
        $('li a', this).click(
            function(e) {
                e.stopImmediatePropagation();
                var theElement = $(this).next();
                var parent = this.parentNode.parentNode;
                if($(parent).hasClass('noaccordion')) {
                    if(theElement[0] === undefined) {
                        window.location.href = this.href;
                    }
                    $(theElement).slideToggle('normal', function() {
                        if ($(this).is(':visible')) {
                            $(this).prev().addClass('active');
                        }
                        else {
                            $(this).prev().removeClass('active');
                        }    
                    });
                    return false;
                }
                else {
                    if(theElement.hasClass('acitem') && theElement.is(':visible')) {
                        if($(parent).hasClass('collapsible')) {
                            $('.acitem:visible', parent).first().slideUp('normal', 
                            function() {
                                $(this).prev().removeClass('active');
                            }
                        );
                        return false;  
                    }
                    return false;
                }
                if(theElement.hasClass('acitem') && !theElement.is(':visible')) {         
                    $('.acitem:visible', parent).first().slideUp('normal', function() {
                        $(this).prev().removeClass('active');
                    });
                    theElement.slideDown('normal', function() {
                        $(this).prev().addClass('active');
                    });
                    return false;
                }
            }
        }
    );
});
};

$(document).ready(function() {$('.menu').initMenu();});

(function($) {
    // PLUGIN DEFINITION
    $.fn.helyenav = function(options) {
        // init plugin and build options before elemnts iteration
        var opts = $.extend({}, $.fn.helyenav.defaults, options);
        $.helyenav.opts = opts;
        $.helyenav.current = opts.current;      
        
        return this.each(function() {
            // execute plugin on each elt
            $.helyenav.init(this, opts);
            $(this).click(onClick);
        });
        
        // private
        function onClick() {
            return $.cookie(opts.cookieName, $.helyenav.current(), { path: opts.cookiePath});
        }
    };

    $.helyenav = {
        init: function(container, opts) {
            var current = $.helyenav.current();
            this.container = container;
            var subnavs = $(container).find(opts.childBlockElt);
            var subnavsNames = $.map(subnavs, function(el) {
                return $(el).parent().attr('class');
            });
            $(subnavs).hide();
            if($.cookie(opts.cookieName) == current){
                subnav(current).show();
            } else {
              $.each(subnavsNames, function(i, name){
                 if($.cookie(opts.cookieName)==name){
                       subnav(name).show();
                       subnav(name).css('display', 'block'); /* for FF2, in case it's inline */
                       subnav(name).slideUp(opts.speed);
                    }
                    if(current==name){
                       subnav(name).slideDown(opts.speed);
                       $.cookie(opts.cookieName, current, { path: opts.cookiePath});
                    }
              });
           }
       
           // private
           function subnav(name){
               return $(this.container).find("." + name + ' > ' + $.helyenav.opts.childBlockElt);
           }
        }
    };
    
    // PLUGIN DEFAULTS
    $.fn.helyenav.defaults = {
        current: function(){ return $('body').attr('class'); },
        speed: 'slow',
        cookieName: 'last',
        cookiePath: '/',
        childBlockElt: 'ul'
    };
    
})(jQuery);

$(document).ready(function($) {
   /* open external links in a new window */
   $('a[rel="external"], a[href^=http]').each(function(){
     if(this.href.indexOf(location.hostname) == -1) { 
        $(this).attr('target', '_blank');
     }
   });
   $('#nav > ul').helyenav();
});