使用WS_SYSMENU样式建立的父窗口，在其标题列的左侧有一个系统菜单按钮。如果您愿意，可以修改这个菜单。在Windows程序设计的早期，程序写作者一般把「About」菜单项放入系统菜单。虽然这种方法不常见，但是修改系统菜单往往是一种在短程序中添加菜单的快速偷懒方法。这里唯一的限制是：在系统菜单中增加的命令其ID值必须小于0xF000；否则它们将会与Windows系统菜单命令所使用的ID值相冲突。还要记住，当您为这些新菜单项在窗口消息处理程序中处理WM_SYSCOMMAND消息时，您必须把其它的WM_SYSCOMMAND消息发送给DefWindowProc。如果您不这样做，那么实际上是禁用了系统菜单上的所有正常选项。
程序10-7 POORMENU POORMENU.C /*------------------------------------------------------------------------- POORMENU.C -- The Poor Person's Menu (c) Charles Petzold, 1998 --------------------------------------------------------------------------*/ #include <windows.h> #define IDM_SYS_ABOUT 1 #define IDM_SYS_HELP 2 #define IDM_SYS_REMOVE 3 LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; static TCHAR szAppName[] = TEXT ("PoorMenu") ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { HMENU hMenu ; HWND hwnd ; MSG msg ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc = WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ; wndclass.lpszMenuName = NULL ; wndclass.lpszClassName = szAppName ; if (!RegisterClass (&wndclass)) { MessageBox ( NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow ( szAppName, TEXT ("The Poor-Person's Menu"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL) ; hMenu = GetSystemMenu (hwnd, FALSE) ; AppendMenu (hMenu, MF_SEPARATOR, 0, NULL) ; AppendMenu (hMenu, MF_STRING, IDM_SYS_ABOUT, TEXT ("About...")) ; AppendMenu (hMenu, MF_STRING, IDM_SYS_HELP, TEXT ("Help...")) ; AppendMenu (hMenu, MF_STRING, IDM_SYS_REMOVE, TEXT ("Remove Additions")) ; ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } LRESULT CALLBACK WndProc ( HWND hwnd, UINT message, WPARAM wParam,LPARAM lParam) { switch (message) { case WM_SYSCOMMAND: switch (LOWORD (wParam)) { case IDM_SYS_ABOUT: MessageBox ( hwnd, TEXT ("A Poor-Person's Menu Program\n") TEXT ("(c) Charles Petzold, 1998"), szAppName, MB_OK | MB_ICONINFORMATION) ; return 0 ; case IDM_SYS_HELP: MessageBox ( hwnd, TEXT ("Help not yet implemented!"), szAppName, MB_OK | MB_ICONEXCLAMATION) ; return 0 ; case IDM_SYS_REMOVE: GetSystemMenu (hwnd, TRUE) ; return 0 ; } break ; case WM_DESTROY: PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; }