问题：一般情况下我们用UPDATE_COMMAND_UI来修改菜单的状态(enable/disable, check/uncheck, change text)，但这个方法在一个基于对话框上的菜单却没有效果。void CTestDlg::OnUpdateFileExit(CCmdUI* pCmdUI) {     pCmdUI->Enable(FALSE);      pCmdUI->SetCheck(TRUE);      pCmdUI->SetRadio(TRUE);      pCmdUI->SetText("Close"); //以上方法在MDI、SDI程序中都能起作用，在对话框中却没有效果,根本没有调用这个函数。} 原因分析：当显示一个下拉的菜单的时候，在显示菜单前会发送WM_INITMENUPOPUP消息。而CFrameWnd::OnInitMenuPopup函数会刷新这个菜单项，同时如果有UPDATE_COMMAND_UI响应函数，则调用它。通过它来更新反应每个菜单的外观效果(enabled/disabled, checked/unchecked).在一个基于对话框的程序中，因为没有OnInitMenuPopup函数，所以不会调用UPDATE_COMMAND_UI响应函数，而是使用了CWnd类的默认处理, 这种处理没有调用UPDATE_COMMAND_UI响应函数。 解决方法如下：第一步：在对话框类的.cpp文件，添加一个ON_WM_INITMENUPOPUP入口到消息映射里面BEGIN_MESSAGE_MAP(CTestDlg, CDialog)//}}AFX_MSG_MAPON_WM_INITMENUPOPUP()END_MESSAGE_MAP()第二步：在对话框类的.h文件添加消息函数声明。// Generated message map functions//{{AFX_MSG(CDisableDlgMenuDlg)afx_msg void OnInitMenuPopup(CMenu *pPopupMenu, UINT nIndex,BOOL bSysMenu);//}}AFX_MSGDECLARE_MESSAGE_MAP()第三步：在对话框类的.cpp文件添加如下函数代码(大部分代码取自WinFrm.cpp文件的函数CFrameWnd::OnInitMenuPopup):void C******Dlg::OnInitMenuPopup(CMenu *pPopupMenu, UINT nIndex,BOOL bSysMenu){     ASSERT(pPopupMenu != NULL);    // Check the enabled state of various menu items.     CCmdUI state;    state.m_pMenu = pPopupMenu;    ASSERT(state.m_pOther == NULL);    ASSERT(state.m_pParentMenu == NULL);     // Determine if menu is popup in top-level menu and set m_pOther to    // it if so (m_pParentMenu == NULL indicates that it is secondary popup).    HMENU hParentMenu;    if (AfxGetThreadState()->m_hTrackingMenu == pPopupMenu->m_hMenu)         state.m_pParentMenu = pPopupMenu;??? // Parent == child for tracking popup.   else if ((hParentMenu = ::GetMenu(m_hWnd)) != NULL)   {       CWnd* pParent = this;       // Child windows don't have menus--need to go to the top!       if (pParent != NULL &&(hParentMenu = ::GetMenu(pParent->m_hWnd)) != NULL)      {           int nIndexMax = ::GetMenuItemCount(hParentMenu);          for (int nIndex = 0; nIndex < nIndexMax; nIndex++)         {             if (::GetSubMenu(hParentMenu, nIndex) == pPopupMenu->m_hMenu)             {                // When popup is found, m_pParentMenu is containing menu.                state.m_pParentMenu = CMenu::FromHandle(hParentMenu);                break;             }         }    }}   state.m_nIndexMax = pPopupMenu->GetMenuItemCount();  for (state.m_nIndex = 0; state.m_nIndex < state.m_nIndexMax;  state.m_nIndex++)  {      state.m_nID = pPopupMenu->GetMenuItemID(state.m_nIndex);      if (state.m_nID == 0)          continue; // Menu separator or invalid cmd - ignore it.       ASSERT(state.m_pOther == NULL);      ASSERT(state.m_pMenu != NULL);      if (state.m_nID == (UINT)-1)      {          // Possibly a popup menu, route to first item of that popup.          state.m_pSubMenu = pPopupMenu->GetSubMenu(state.m_nIndex);          if (state.m_pSubMenu == NULL || (state.m_nID = state.m_pSubMenu->GetMenuItemID(0)) == 0 ||state.m_nID == (UINT)-1)       {              continue;    // First item of popup can't be routed to.       }       state.DoUpdate(this, TRUE);?? // Popups are never auto disabled.      }      else     {          // Normal menu item.          // Auto enable/disable if frame window has m_bAutoMenuEnable          // set and command is _not_ a system command.         state.m_pSubMenu = NULL;         state.DoUpdate(this, FALSE);      }       // Adjust for menu deletions and additions.      UINT nCount = pPopupMenu->GetMenuItemCount();      if (nCount < state.m_nIndexMax)        {                   state.m_nIndex -= (state.m_nIndexMax - nCount);                   while (state.m_nIndex < nCount &&                  pPopupMenu->GetMenuItemID(state.m_nIndex) == state.m_nID)           {            state.m_nIndex++;            }       }        state.m_nIndexMax = nCount;   }}

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