Fix application dispose issue

Author: Jack251970

Flow.Launcher/App.xaml.cs

@@ -138,6 +138,11 @@ private async void OnStartup(object sender, StartupEventArgs e)
         {
             await Stopwatch.NormalAsync("|App.OnStartup|Startup cost", async () =>
             {
+                // Because new message box api uses MessageBoxEx window,
+                // if it is created and closed before main window is created, it will cause the application to exit.
+                // So set to OnExplicitShutdown to prevent the application from shutting down before main window is created
+                Current.ShutdownMode = ShutdownMode.OnExplicitShutdown;
+
                 Log.SetLogLevel(_settings.LogLevel);
 
                 Ioc.Default.GetRequiredService<Portable>().PreStartCleanUpAfterPortabilityUpdate();