How Can I Keep My Application Running After Closing the Startup Form?

Keeping Your Application Active After Closing the Startup Form

You likely encountered an issue where closing the initial form (Form1) also terminated the entire application, even if other forms (like Form2) were open. This is because the application's lifecycle is tied to the main form.

Simply hiding Form1 instead of closing it keeps the application running, but introduces a problem: the application won't close gracefully when Form2 is closed.

The solution lies in modifying the Program.cs code, which controls the application's shutdown behavior. Here's the adjusted code to keep the application running after the initial form is closed:

<code class="language-csharp">    [STAThread]
    static void Main() {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Form1 main = new Form1();
        main.FormClosed += FormClosed;
        main.Show();
        Application.Run();
    }

    static void FormClosed(object sender, FormClosedEventArgs e) {
        ((Form)sender).FormClosed -= FormClosed; //Detach event handler
        if (Application.OpenForms.Count == 0) {
            Application.ExitThread(); // Exit only when all forms are closed
        } else {
            Application.OpenForms[0].FormClosed += FormClosed; // Attach to the next open form
        }
    }</code>

This improved code does the following:

• Event Handling: The FormClosed event handler is attached to the initial form (Form1).
• Form Closure Monitoring: It checks if any forms are still open after a form closes.
• Graceful Shutdown: If no forms remain (Application.OpenForms.Count == 0), Application.ExitThread() gracefully shuts down the application.
• Event Handler Reattachment: If other forms are open, the FormClosed event handler is attached to the next open form, ensuring continued monitoring.

This approach allows Form2 to remain open after closing Form1, and the application will only terminate when all forms are closed.

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