win32创建窗口，点击“非模式对话框”该菜单项时，在主菜单条下添加一个弹出式菜单“对话框”，下面有菜单项，分别为“打开”、“关闭”、分隔线和“删除菜单”，初始情况下“删除菜单”为不可用

以下是示例代码：

#include <windows.h>

// 全局变量
HINSTANCE hInst; // 当前实例句柄
HWND hWndMain; // 主窗口句柄

// 菜单命令 ID
#define IDM_OPEN 101
#define IDM_CLOSE 102
#define IDM_SEPARATOR 103
#define IDM_DELETE 104

// 窗口过程
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COMMAND:
        switch (LOWORD(wParam))
        {
        case IDM_OPEN:
            MessageBox(hWnd, TEXT("打开对话框"), TEXT("提示"), MB_OK);
            break;
        case IDM_CLOSE:
            MessageBox(hWnd, TEXT("关闭对话框"), TEXT("提示"), MB_OK);
            break;
        case IDM_DELETE:
            MessageBox(hWnd, TEXT("删除菜单"), TEXT("提示"), MB_OK);
            break;
        }
        break;
    case WM_CREATE:
        {
            // 创建“对话框”弹出式菜单
            HMENU hMenuPopup = CreatePopupMenu();
            AppendMenu(hMenuPopup, MF_STRING, IDM_OPEN, TEXT("打开"));
            AppendMenu(hMenuPopup, MF_STRING, IDM_CLOSE, TEXT("关闭"));
            AppendMenu(hMenuPopup, MF_SEPARATOR, IDM_SEPARATOR, NULL);
            AppendMenu(hMenuPopup, MF_GRAYED | MF_STRING, IDM_DELETE, TEXT("删除菜单"));

            // 添加“非模式对话框”菜单项
            HMENU hMenu = GetMenu(hWnd);
            AppendMenu(hMenu, MF_STRING | MF_POPUP, (UINT_PTR)hMenuPopup, TEXT("对话框"));
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

// WinMain 入口函数
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    // 注册窗口类
    WNDCLASSEX wcex = { sizeof(WNDCLASSEX) };
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.hInstance = hInstance;
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.lpszClassName = TEXT("MainWindowClass");
    RegisterClassEx(&wcex);

    // 创建主窗口
    hInst = hInstance;
    hWndMain = CreateWindow(TEXT("MainWindowClass"), TEXT("Win32 Window"), WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 640, 480, NULL, NULL, hInstance, NULL);
    if (!hWndMain)
    {
        return FALSE;
    }

    // 显示主窗口
    ShowWindow(hWndMain, nCmdShow);
    UpdateWindow(hWndMain);

    // 消息循环
    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int)msg.wParam;
}

在主窗口的创建过程中，创建一个弹出式菜单，并添加菜单项。在窗口过程中，处理菜单命令，并显示相应的提示框。在“删除菜单”菜单项上设置 MF_GRAYED 标志，使其不可用。