(function () {

    // The initially selected tab will be chosen in the following order:
    //
    // URL fragment identifier (it will be there if the user previously
    // bookmarked the application in a specific state)
    //
    //         or
    //
    // "tab0" (default)

    var bookmarkedTabViewState = YAHOO.util.History.getBookmarkedState("tabview");
    var initialTabViewState = bookmarkedTabViewState || "tab0";

    var tabView;

    // Register our TabView module. Module registration MUST
    // take place before calling YAHOO.util.History.initialize.
    YAHOO.util.History.register("tabview", initialTabViewState, function (state) {
        // This is called after calling YAHOO.util.History.navigate, or after the user
        // has trigerred the back/forward button. We cannot discrminate between
        // these two situations.

        // "state" can be "tab0", "tab1" or "tab2".
        // Select the right tab:
        tabView.set("activeIndex", state.substr(3));
    });

    function handleTabViewActiveTabChange (e) {
        var newState, currentState;

        newState = "tab" + this.getTabIndex(e.newValue);

        try {
            currentState = YAHOO.util.History.getCurrentState("tabview");
            // The following test is crucial. Otherwise, we end up circling forever.
            // Indeed, YAHOO.util.History.navigate will call the module onStateChange
            // callback, which will call tabView.set, which will call this handler
            // and it keeps going from here...
            if (newState != currentState) {
                YAHOO.util.History.navigate("tabview", newState);
            }
        } catch (e) {
            tabView.set("activeIndex", newState.substr(3));
        }
    }

    function initTabView () {
        // Instantiate the TabView control...
        tabView = new YAHOO.widget.TabView("demo");
        tabView.addListener("activeTabChange", handleTabViewActiveTabChange);
    }

    // Use the Browser History Manager onReady method to instantiate the TabView widget.
    YAHOO.util.History.onReady(function () {
        var currentState;

        initTabView();

        // This is the tricky part... The onLoad event is fired when the user
        // comes back to the page using the back button. In this case, the
        // actual tab that needs to be selected corresponds to the last tab
        // selected before leaving the page, and not the initially selected tab.
        // This can be retrieved using getCurrentState:
        currentState = YAHOO.util.History.getCurrentState("tabview");
        tabView.set("activeIndex", currentState.substr(3));
    });

    // Initialize the browser history management library.
    try {
        YAHOO.util.History.initialize("yui-history-field", "yui-history-iframe");
    } catch (e) {
        // The only exception that gets thrown here is when the browser is
        // not supported (Opera, or not A-grade) Degrade gracefully.
        initTabView();
    }

})();