OpenFileDialog does not open after a WPF window was closed

Question

I need to show a WPF window and, after a user closes it, an OpenFileDialog. The Window1 is a window that has only one button with a Close() method. The OpenFileDialog does not open if a WPF window has been opened before. How to fix it?

public partial class App : Application
{
void ApplicationOnStartup(object sender, StartupEventArgs args)
{
// If I remove comments and window opens, the OpenFileDialog will not
// Window1 window1 = new();
// window1.ShowDialog();

OpenFileDialog folderBrowser = new();
bool? test = folderBrowser.ShowDialog(); // true/false if the dialog was opened; false if window was opened before
}
}

Answer 1

I don't know how well I understood you. Try these two options:

public partial class App : Application
{
    void ApplicationOnStartup(object sender, StartupEventArgs args)
    {
        MainWindow = new Window1();
        MainWindow.Show();

        OpenFileDialog folderBrowser = new();
        bool? test = folderBrowser.ShowDialog(); 
    }
}

public partial class App : Application
{
    void ApplicationOnStartup(object sender, StartupEventArgs args)
    {
        Window window1 = new();
        window1.Loaded += OpenFileDialogAfterLoadedWindow;
        window1.ShowDialog();
    }
    private static void OpenFileDialogAfterLoadedWindow(object sender, RoutedEventArgs e)
    {
        // First, turn off the wiretap so that there were no repeated calls (this is rare, but possible).
        Window window = (Window)sender;
        window.Loaded -= OpenFileDialogAfterLoadedWindow;

        OpenFileDialog folderBrowser = new();
        bool? test = folderBrowser.ShowDialog();

        // Some Code
    }
}

Perhaps I misunderstood you, and the problem is that you have the value of the ShutdownMode property set incorrectly.
If so, then this code:

public partial class App : Application
{
    void ApplicationOnStartup(object sender, StartupEventArgs args)
    {
        ShutdownMode = ShutdownMode.OnExplicitShutdown;
        Window1 window1 = new();
        window1.ShowDialog();

        OpenFileDialog folderBrowser = new();
        bool? test = folderBrowser.ShowDialog(); // true/false if the dialog was opened; false if window was opened before

        // You need to explicitly close the application.
        Shutdown();

        // Or create a window and change the application close mode.
        MainWindow = new SomeWindow();
        ShutdownMode = ShutdownMode.OnMainWindowClose;
        MainWindow.Show();
    }
}