/// <summary>
        /// Calle when [unloaded].
        /// </summary>
        /// <param name="sender">The source of the event.</param>
        /// <param name="e">An <see cref="T:System.Windows.RoutedEventArgs">RoutedEventArgs</see> that contains the event data.</param>
        /// <remarks></remarks>
        private void OnUnloaded(object sender, RoutedEventArgs e)
        {
            this.Unloaded -= OnUnloaded;
            this.Loaded   -= OnLoaded;
            if (richTextRibbon != null)
            {
                richTextRibbon.Loaded -= RichTextRibbon_Loaded;
                richTextRibbon.Dispose();
                richTextRibbon = null;
            }
            if (richTextBoxAdv != null)
            {
                richTextBoxAdv.SelectionChanged -= RichTextBoxAdv_SelectionChanged;
                richTextBoxAdv.RequestNavigate  -= RichTextBoxAdv_RequestNavigate;
                richTextBoxAdv.Dispose();
                richTextBoxAdv = null;
            }

            if (skinTab != null)
            {
                skinTab.Dispose();
                skinTab = null;
            }
        }