/* -----------------------------------------------------------------------*/
function AddEvent(targetObj, eventName, eventHandler) {
    if (document.addEventListener){
        targetObj.addEventListener(eventName, eventHandler, false);
        return;
    }
    if (document.attachEvent){
        targetObj.attachEvent("on"+eventName, eventHandler);
    }
}

AddEvent(window, "load", function() {
        var tab01 = document.getElementById("tab01");
        var tab02 = document.getElementById("tab02");
        var tab03 = document.getElementById("tab03");
        var tab04 = document.getElementById("tab04");

        var cat01 = document.getElementById("category01");
        var cat02 = document.getElementById("category02");
        var cat03 = document.getElementById("category03");
        var cat04 = document.getElementById("category04");

        if(!(tab01 || tab02 || tab03 || tab04 )) return false;

        AddEvent(tab01, "click", function(event){
                
                cat01.className = "stay";
                cat02.className = "";
                cat03.className = "";
                cat04.className = "";

                tab01.className = "stay";
                tab02.className = "";
                tab03.className = "";
                tab04.className = "";

                if (!event){
                    event = window.event;
                }
                if (event.preventDefault) {
                    event.preventDefault();
                }else {
                    event.returnValue = false;
                }

                return false;
        });
        AddEvent(tab02, "click", function(event){

                cat01.className = "";
                cat02.className = "stay";
                cat03.className = "";
                cat04.className = "";

                tab01.className = "";
                tab02.className = "stay";
                tab03.className = "";
                tab04.className = "";

                if (!event){
                    event = window.event;
                }
                if (event.preventDefault) {
                    event.preventDefault();
                }else {
                    event.returnValue = false;
                }

                return false;
        });
        AddEvent(tab03, "click", function(event){
                cat01.className = "";
                cat02.className = "";
                cat03.className = "stay";
                cat04.className = "";

                tab01.className = "";
                tab02.className = "";
                tab03.className = "stay";
                tab04.className = "";

                if (!event){
                    event = window.event;
                }
                if (event.preventDefault) {
                    event.preventDefault();
                }else {
                    event.returnValue = false;
                }

                return false;
        });
        AddEvent(tab04, "click", function(event){

                cat01.className = "";
                cat02.className = "";
                cat03.className = "";
                cat04.className = "stay";

                tab01.className = "";
                tab02.className = "";
                tab03.className = "";
                tab04.className = "stay";

                if (!event){
                    event = window.event;
                }
                if (event.preventDefault) {
                    event.preventDefault();
                }else {
                    event.returnValue = false;
                }

                return false;
        });
});