void OnUpdateInstalled( object sender, HelpUpdateDownloadedEventArgs e )
 {
     var vm = FindOrCreateVm( e.Plugin );
     vm.State = PluginUpdateState.Installed;
 }
 void OnUpdateDownloaded( object sender, HelpUpdateDownloadedEventArgs e )
 {
     var vm = FindOrCreateVm( e.Plugin );
     vm.State = PluginUpdateState.WaitingForInstall;
     vm.DownloadResult = e.DownloadResult;
 }