wpf- Application_Startup - 加载对话窗口然后是主窗口

I have a wpf application and I created a logon window which is used to build the application's connection string. I am having issues closing the first dialog and spinning open the MainWindow behind it. I think a close event is bubbling out of the logon dialog and getting stuck in the MainWindow because as soon as I create the MainWindow object in the codebehind and call Show() it just moves right past my Startup event handler and into my constructor then the onClosing handlers of the MainWindow without ever showing the window itself. The app.xaml has the ShutdownMode="OnMainWindowClose" specified.I have a wpf application and I created a logon