为什么我无法检测到发送到我的 CommonDialog 的 Windows 消息？拦截它们的正确方法是什么？

我试图检测用户何时点击 aForm和 a CommonDialog。

表格相当简单。我创建了一个MessageFilter拦截消息的类：

class MessageFilter : IMessageFilter
{
    private const int WM_LBUTTONDOWN = 0x0201;
    public bool PreFilterMessage(ref Message message)
    {
        if (message.Msg == WM_LBUTTONDOWN)
        {
            Console.WriteLine("activity");
        }
        return false;
    }
}

我注册了消息过滤器：

MessageFilter mf = new MessageFilter();
Application.AddMessageFilter(mf);

Form form = new Form();
form.ShowDialog();

Application.RemoveMessageFilter(mf)

当我运行我的控制台应用程序并单击 时Form，我看到“活动”记录到控制台。

当我替换Form为CommonDialog：

SaveFileDialog dialog = new SaveFileDialog();
dialog.ShowDialog();

即使我可以看到 Windows 消息被发送到 CommonDialog（FWIW，我无法检测到任何消息），我也无法再检测到鼠标点击：

那我怎么不能拦截那些消息呢？

我想到的是，由于Application.AddMessageFilter是线程特定的，也许如果 CommonDialog 是在与调用 的线程不同的线程上创建的dialog.ShowDialog()，我将不会收到任何这些消息。

但是，我做了一个快速测试，我尝试向WM_CLOSE调用 的线程上的所有 CommonDialogs发送一条消息dialog.ShowDialog()，并且成功了：

int threadId = 0;
Thread thread = new Thread(() =>
{
    threadId = NativeMethods.GetCurrentThreadIdWrapper();
    SaveFileDialog dialog = new SaveFileDialog();
    dialog.ShowDialog();
});
thread.SetApartmentState(ApartmentState.STA);
thread.Start();

Thread.Sleep(2000);
NativeMethods.CloseAllWindowsDialogs(threadId);
Thread.Sleep(2000);

NativeMethods 看起来像：

static class NativeMethods
{
    public static int GetCurrentThreadIdWrapper()
    {
        return GetCurrentThreadId();
    }

    public static void CloseAllWindowsDialogs(int threadId)
    {
        EnumThreadWndProc callback = new EnumThreadWndProc(CloseWindowIfCommonDialog);
        EnumThreadWindows(threadId, callback, IntPtr.Zero);
        GC.KeepAlive(callback);
    }

    private static bool CloseWindowIfCommonDialog(IntPtr hWnd, IntPtr lp)
    {
        if (IsWindowsDialog(hWnd))
        {
            UIntPtr result;
            const int WM_CLOSE = 0x0010;
            const uint SMTO_ABORTIFHUNG = 0x0002;
            SendMessageTimeout(hWnd, WM_CLOSE, UIntPtr.Zero, IntPtr.Zero, SMTO_ABORTIFHUNG, 5000, out result);
        }

        return true;
    }

    private static bool IsWindowsDialog(IntPtr hWnd)
    {
        const int MAX_PATH_LENGTH = 260; // https://docs.microsoft.com/en-us/windows/desktop/FileIO/naming-a-file#maximum-path-length-limitation
        StringBuilder sb = new StringBuilder(MAX_PATH_LENGTH);
        GetClassName(hWnd, sb, sb.Capacity);

        return sb.ToString() == "#32770";
    }

    [DllImport("kernel32.dll", SetLastError = true)]
    private static extern int GetCurrentThreadId();

    private delegate bool EnumThreadWndProc(IntPtr hWnd, IntPtr lp);

    [DllImport("user32.dll", SetLastError = true)]
    private static extern bool EnumThreadWindows(int tid, EnumThreadWndProc callback, IntPtr lp);

    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    private static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);

    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    private static extern IntPtr SendMessageTimeout(IntPtr hWnd, uint msg, UIntPtr wp, IntPtr lp, uint fuFlags, uint timeout, out UIntPtr lpdwResult);
}

为什么我不能拦截 CommonDialog 消息？我能做些什么？