/// <summary>
        /// left click on the folder. adds the email to the emailList in the mainwindow
        /// </summary>
        /// <param name="sender">sender</param>
        /// <param name="e">event</param>
        private void headerTreeItem_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            mw.emailList.Children.Clear();
            string headerText = folderName;

            if (folderName.Contains('(') && folderName.Contains(')'))
            {
                headerText = folderName.Substring(0, folderName.IndexOf('(')).Trim();
            }
            EmailListShower els = new EmailListShower(emails, headerText, mw);

            mw.emailList.Children.Add(els);
        }
 /// <summary>
 /// left click on the folder. adds the email to the emailList in the mainwindow  
 /// </summary>
 /// <param name="sender">sender</param>
 /// <param name="e">event</param>
 private void headerTreeItem_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
 {
     mw.emailList.Children.Clear();
     string headerText = folderName;
     if (folderName.Contains('(') && folderName.Contains(')'))
     {
         headerText = folderName.Substring(0, folderName.IndexOf('(')).Trim();
     }
     EmailListShower els = new EmailListShower(emails, headerText, mw);
     mw.emailList.Children.Add(els);
 }