private async void _RunUpdateChecker(bool background_check)
        {
            // Do update check, with or without a progress dialog
            ProgressDialog progress = null;

            if (!background_check)
            {
                progress = new ProgressDialog(this, " ");
                progress.CounterFormat = "";
                progress.Interval      = 0;
                progress.Events.Start(-1, Translate._("MainWindow.UpdateCheck.Progress.Title"), " ");
            }

            string        changelog = null;
            Task <string> check     = Task.Run(() => {
                string vers_url = string.Format("{0}?u={1}&v={2}",
                                                Helpers.Unpack("yygpKSi20tc3STNKsUw008vPy8nMS9UtTi0qSy3SS87JL03RL8vxM0jzjAop8IhMTDL2MPDITc/QB0oXZ+bn6WbmpeXrVeTmAAA="),
                                                Settings.USER_KEY, Settings.APPVERSION.Replace(" ", "_"));
                UpdateChecker checker = new UpdateChecker(vers_url, progress != null? progress.Events : null, Logger.LOG);
                string url            = checker.Check(Settings.APPTITLE, Settings.APPVERSION, out changelog);
                checker.Close();
                checker = null;
                return(url);
            });
            await  check;
            string dl_url = check.Result;

            if (progress != null)
            {
                progress.Close();
            }
            progress = null;

            if (string.IsNullOrEmpty(dl_url))
            {
                if (!background_check)
                {
                    MessageBox.Show(Translate._("MainWindow.UpdateCheck.NoUpdateAvail"), Translate._("MainWindow.UpdateCheck.Title"));
                }
                return;
            }

            // Prompt user to continue installation
            bool update = false;

            if (string.IsNullOrEmpty(changelog))
            {
                var ret = MessageBox.Show(Translate._("MainWindow.UpdateCheck.NewVersionAvail"),
                                          Translate._("MainWindow.UpdateCheck.Title"), MessageBoxButton.YesNo, MessageBoxImage.Question);
                update = (ret == MessageBoxResult.Yes);
            }
            else
            {
                string[] buttons = new string[] { Translate._("Yes"), Translate._("No"),
                                                  Translate._("MainWindow.UpdateCheck.NewVersionAvail") };
                update = ShowHtmlResDialog.Show(Translate._("MainWindow.UpdateCheck.Title"), changelog, buttons);
            }
            if (!update)
            {
                return;
            }

            // Download installer package, ...
            string dest_file = Path.Combine(Settings.APPPATH, Path.GetFileName(dl_url));

            using (Stream strm = File.Create(dest_file))
            {
                Downloader dl = new Downloader(dl_url, null, Logger.LOG);
                if (!dl.Download(strm))
                {
                    MessageBox.Show(Translate._("MainWindow.UpdateCheck.DownloadFailed"), Translate._("MainWindow.UpdateCheck.Title"));
                    return;
                }
            }
            // ..., and start installer in silent mode (installer will wait until program has closed)
            ProcessStartInfo info = new ProcessStartInfo()
            {
                FileName         = dest_file,
                Arguments        = "/S",
                WorkingDirectory = Settings.APPPATH,
                UseShellExecute  = false,
                ErrorDialog      = false,
            };
            Process process = Process.Start(info);

            if (process == null || process.HasExited)
            {
                MessageBox.Show(Translate._("MainWindow.UpdateCheck.InstallFailed"), Translate._("MainWindow.UpdateCheck.Title"));
                if (process != null)
                {
                    process.Dispose();
                }
                return;
            }

            // End program and let installer do its job
            Close();
        }