internal static class Program

{

/// <summary>

/// Main method – guards against multiple instances, enables WinForms

/// visual styles, and starts the UI via <see cref="AppContextManager" />.

/// </summary>

[STAThread]

static void Main()

{

// Unique name for the mutex that enforces a single instance.

string SingleInstanceMutexName = Application.ProductName;

// Try to acquire the global mutex.

bool isFirstInstance;

using var mutex = new Mutex(initiallyOwned: true,

name: SingleInstanceMutexName,

createdNew: out isFirstInstance);

if (!isFirstInstance) return; // Another copy is already running – quietly exit.

Application.EnableVisualStyles();

Application.SetCompatibleTextRenderingDefault(false);

Application.Run(new AppContextManager());

// GC.KeepAlive(mutex); // Now unnecessary with the using‑statement.

}

#region Nested ApplicationContext

/// <summary>

/// Custom context lets us close and reopen <see cref="MainForm"/> without

/// killing the message loop or losing the single‑instance mutex.

/// </summary>

private sealed class AppContextManager : ApplicationContext

{

public AppContextManager() => ShowMain();

/// <summary>

/// Instantiates and shows a new <see cref="MainForm"/>.

/// </summary>

private void ShowMain()

{

var main = new MainForm();

this.MainForm = main; // Let ApplicationContext watch it.

// Event handler that restores native chrome and restarts form.

void RestoreHandler(object? sender, EventArgs e)

{

main.RestoreNativeRequested -= RestoreHandler;

main.FormClosed -= Main_FormClosed;

main.Close(); // Dispose current form.

ShowMain(); // Open a fresh one.

}

// Wire up events.

main.RestoreNativeRequested += RestoreHandler;

main.FormClosed += (s, e) => ExitThread(); // Keep handler.

// Show the window (non‑modal).

main.Show();

}

/// <summary>

/// Ends the message loop when the main form closes.

/// </summary>

private void Main_FormClosed(object? sender, FormClosedEventArgs e) =>

ExitThread(); // Base class method – stops Application.Run.

}

#endregion

}