private void ShareFileAsync(string[] filenames)
 {
     foreach (string filename in filenames)
     {
         try
         {
             _chat.ShareFile(filename);
         }
         catch (Exception ex)
         {
             MessageBox.Show("Error encountered while sharing file.\r\n\r\n" + ex.Message, "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
         }
     }
 }