C# 从控件创建父窗体WndProc的子类

我正在将自定义MenuStrip控件集成到另一个.NET应用程序中。MenuStrip工作正常，但有一个焦点问题。如果承载MenuStrip的表单没有焦点，用户需要单击两次-一次激活表单，另一次选择菜单项。主机窗体是单独的.NET应用程序的一部分，我无法修改它。我只能修改控件的源代码

我发现了一个重写表单WndProc方法的方法，但我没有WinForm的源代码访问权限，也无法重新编译宿主应用程序和表单

---

有没有办法对控件的父窗体进行子类化，以便它在未聚焦时自动激活父窗体？

我可以使用ContainerControl.ParentForm获取对宿主窗体的引用，但是在生产环境中父窗体返回null，我仍然需要找到解决方案。我将NewWndProc处理程序放在try/catch中，以防它抛出任何异常，尽管我不确定它可能抛出什么（如果有的话）。我可能只能使用Win32函数，而不能使用Form.Focused和Form.Activate（）.NET方法。无论如何，代码如下：

public class FocusFormWrapper
{
    #region DllImport
    public const int GWL_WNDPROC = (-4);
    public const UInt32 WM_CLOSE = 0x0010;
    public const UInt32 WM_PARENTNOTIFY = 0x0210; 

    public delegate IntPtr WndProcDelegate(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool IsWindow(IntPtr hWnd);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr GetWindowLong(IntPtr hWnd, int nIndex);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr newWndProc);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern IntPtr CallWindowProc(IntPtr lpPrevWndFunc, IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern IntPtr FindWindow(string _ClassName, string _WindowName);

    [DllImport("user32.dll", SetLastError = true)]
    public static extern int SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool SetForegroundWindow(IntPtr hWnd);
    #endregion DllImport

    private Form myForm = null;
    private IntPtr hWndTarget = IntPtr.Zero;
    private IntPtr oldWndProc = IntPtr.Zero;
    private WndProcDelegate newWndProc;

    private FocusFormWrapper()
    {
    }

    public FocusFormWrapper(Form sourceForm)
    {
        if (sourceForm == null)
            throw new ArgumentNullException("sourceForm");
        if (!IsWindow(sourceForm.Handle))
            throw new ArgumentException("sourceForm IsWindow failed");

        myForm = sourceForm;
        hWndTarget = myForm.Handle;
        AddSubclass();
    }

    ~FocusFormWrapper()
    {
        RemoveSubclass();
        myForm = null;
        newWndProc = null;
    }

    private int AddSubclass()
    {
        int result = -1;
        if (myForm != null && newWndProc == null)
        {
            newWndProc = new WndProcDelegate(NewWndProc);
            oldWndProc = GetWindowLong(hWndTarget, GWL_WNDPROC);
            result = SetWindowLong(hWndTarget, GWL_WNDPROC, Marshal.GetFunctionPointerForDelegate(newWndProc));
        }
        return result;
    }

    public int RemoveSubclass()
    {
        int result = -1;
        if (myForm != null && newWndProc != null)
        {
            result = SetWindowLong(hWndTarget, GWL_WNDPROC, oldWndProc);
            newWndProc = null;
        }
        return result;
    }

    public IntPtr NewWndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam)
    {
        try
        {
            if (msg == WM_PARENTNOTIFY && !myForm.Focused)
            {
                // Make this form auto-grab the focus when menu/controls are clicked 
                myForm.Activate();
            }
            if (msg == WM_CLOSE)
            {
                RemoveSubclass();
            }
        }
        catch
        {
        }

        return CallWindowProc(oldWndProc, hWnd, msg, wParam, lParam);
    }
}