var categories = new Array("1", "2");
                        function Display(id) {
                                if(document.getElementById(id).style.display == "none") {
                                        for(i = 0; i < categories.length; i++)
                                                if(document.getElementById("category_" + categories[i]).style.display == "block") {
                                                        document.getElementById("category_" + categories[i]).style.display = "none";

                                                }
                                        document.getElementById(id).style.display = "block";
                                       ;
                                } else {
                                        document.getElementById(id).style.display = "none";

                                }
                        }