/// <summary>
    /// Fills check box list with current values
    /// </summary>
    private void FillItems()
    {
        var items = OutputCache ? GetOutputCacheItemNames() : PartialCacheItemsProvider.GetCacheItemNames();

        foreach (var item in items)
        {
            ListItem li = new ListItem(item.Key, item.Key);
            chkList.Items.Add(li);
            li.Selected = item.Value;
        }
    }
    /// <summary>
    /// OnLoad handler. Ensures button click handler and error message.
    /// </summary>
    /// <param name="e"></param>
    protected override void OnLoad(EventArgs e)
    {
        // Display error if values are loaded from web.config
        if (!String.IsNullOrEmpty(SettingsHelper.AppSettings[OutputCache ? "CMSOutputCacheItems" : "CMSPartialCacheItems"]))
        {
            lblError.Visible = true;
            lblError.Text    = GetString("cacheitems.appvalues");
        }

        // Handle click event
        btnSelect.Click += btnSelect_Click;

        // Load text values
        if (!RequestHelper.IsPostBack())
        {
            txtItems.Text = OutputCache ? OutputHelper.CacheItems : PartialCacheItemsProvider.GetEnabledCacheItems();
        }

        base.OnLoad(e);
    }