MFC MDI框架中自定义Toolbar停靠触发断言错误求助

在MFC MDI程序的CMainFrame::OnCreate方法中添加自定义工具栏m_wndColorBar的停靠代码后，编译正常但运行时触发Debug Assertion Failed错误，此前程序无异常。

出现问题的OnCreate代码 #

int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
    if (CMDIFrameWndEx::OnCreate(lpCreateStruct) == -1)
        return -1;

    BOOL bNameValid;

    CMDITabInfo mdiTabParams;
    mdiTabParams.m_style = CMFCTabCtrl::STYLE_3D_ONENOTE; 
    mdiTabParams.m_bActiveTabCloseButton = TRUE;      
    mdiTabParams.m_bTabIcons = FALSE;    
    mdiTabParams.m_bAutoColor = TRUE;    
    mdiTabParams.m_bDocumentMenu = TRUE; 
    EnableMDITabbedGroups(TRUE, mdiTabParams);

    if (!m_wndMenuBar.Create(this))
    {
        TRACE0("Failed to create menubar\n");
        return -1;      
    }

    m_wndMenuBar.SetPaneStyle(m_wndMenuBar.GetPaneStyle() | CBRS_SIZE_DYNAMIC | CBRS_TOOLTIPS | CBRS_FLYBY);

    CMFCPopupMenu::SetForceMenuFocus(FALSE);

    if (!m_wndToolBar.CreateEx(this, TBSTYLE_FLAT, WS_CHILD | WS_VISIBLE | CBRS_TOP | CBRS_GRIPPER | CBRS_TOOLTIPS | CBRS_FLYBY | CBRS_SIZE_DYNAMIC) ||
        !m_wndToolBar.LoadToolBar(theApp.m_bHiColorIcons ? IDR_MAINFRAME_256 : IDR_MAINFRAME))
    {
        TRACE0("Failed to create toolbar\n");
        return -1;      
    }

    CString strToolBarName;
    bNameValid = strToolBarName.LoadString(IDS_TOOLBAR_STANDARD);
    ASSERT(bNameValid);
    m_wndToolBar.SetWindowText(strToolBarName);

    CString strCustomize;
    bNameValid = strCustomize.LoadString(IDS_TOOLBAR_CUSTOMIZE);
    ASSERT(bNameValid);
    m_wndToolBar.EnableCustomizeButton(TRUE, ID_VIEW_CUSTOMIZE, strCustomize);

    InitUserToolbars(nullptr, uiFirstUserToolBarId, uiLastUserToolBarId);

    if (!m_wndStatusBar.Create(this))
    {
        TRACE0("Failed to create status bar\n");
        return -1;      
    }
    m_wndStatusBar.SetIndicators(indicators, sizeof(indicators)/sizeof(UINT));

    int iTBCtlID;
    if (!m_wndColorBar.CreateEx(this, TBSTYLE_FLAT, WS_CHILD | WS_VISIBLE | CBRS_TOP | CBRS_GRIPPER | CBRS_TOOLTIPS | CBRS_FLYBY | CBRS_SIZE_DYNAMIC) ||
        !m_wndColorBar.LoadToolBar(IDR_TBCOLOR))
    {
        TRACE0("Failed to Create toolbar \n");
        return -1;
    }

    iTBCtlID = m_wndColorBar.CommandToIndex(ID_COLORS_BLACK);
    if (iTBCtlID >= 0)
    {
        for (int i = iTBCtlID; i < (iTBCtlID + 11); i++)
            m_wndColorBar.SetButtonStyle(i, TBBS_CHECKGROUP);
    }

    m_wndMenuBar.EnableDocking(CBRS_ALIGN_ANY);
    m_wndToolBar.EnableDocking(CBRS_ALIGN_ANY);
    m_wndColorBar.EnableDocking(CBRS_ALIGN_ANY);

    EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndMenuBar);
    DockPane(&m_wndToolBar);

    CDockingManager::SetDockingMode(DT_SMART);
    EnableAutoHidePanes(CBRS_ALIGN_ANY);

    CMFCToolBar::AddToolBarForImageCollection(IDR_MENU_IMAGES, theApp.m_bHiColorIcons ? IDB_MENU_IMAGES_24 : 0);

    if (!CreateDockingWindows())
    {
        TRACE0("Failed to create docking windows\n");
        return -1;
    }

    m_wndFileView.EnableDocking(CBRS_ALIGN_ANY);
    m_wndClassView.EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndFileView);
    CDockablePane* pTabbedBar = nullptr;
    m_wndClassView.AttachToTabWnd(&m_wndFileView, DM_SHOW, TRUE, &pTabbedBar);
    m_wndOutput.EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndOutput);
    m_wndProperties.EnableDocking(CBRS_ALIGN_ANY);
    DockPane(&m_wndProperties);

    OnApplicationLook(theApp.m_nAppLook);

    EnableWindowsDialog(ID_WINDOW_MANAGER, ID_WINDOW_MANAGER, TRUE);

    EnablePaneMenu(TRUE, ID_VIEW_CUSTOMIZE, strCustomize, ID_VIEW_TOOLBAR);

    CMFCToolBar::EnableQuickCustomization();

    if (CMFCToolBar::GetUserImages() == nullptr)
    {
        if (m_UserImages.Load(_T(".\\UserImages.bmp")))
        {
            CMFCToolBar::SetUserImages(&m_UserImages);
        }
    }

    CList<UINT, UINT> lstBasicCommands;

    lstBasicCommands.AddTail(ID_FILE_NEW);
    lstBasicCommands.AddTail(ID_FILE_OPEN);
    lstBasicCommands.AddTail(ID_FILE_SAVE);
    lstBasicCommands.AddTail(ID_FILE_PRINT);
    lstBasicCommands.AddTail(ID_APP_EXIT);
    lstBasicCommands.AddTail(ID_EDIT_CUT);
    lstBasicCommands.AddTail(ID_EDIT_PASTE);
    lstBasicCommands.AddTail(ID_EDIT_UNDO);
    lstBasicCommands.AddTail(ID_APP_ABOUT);
    lstBasicCommands.AddTail(ID_VIEW_STATUS_BAR);
    lstBasicCommands.AddTail(ID_VIEW_TOOLBAR);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2003);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_VS_2005);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_BLUE);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_SILVER);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_BLACK);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_OFF_2007_AQUA);
    lstBasicCommands.AddTail(ID_VIEW_APPLOOK_WINDOWS_7);
    lstBasicCommands.AddTail(ID_SORTING_SORTALPHABETIC);
    lstBasicCommands.AddTail(ID_SORTING_SORTBYTYPE);
    lstBasicCommands.AddTail(ID_SORTING_SORTBYACCESS);
    lstBasicCommands.AddTail(ID_SORTING_GROUPBYTYPE);

    CMFCToolBar::SetBasicCommands(lstBasicCommands);

    ModifyStyle(0, FWS_PREFIXTITLE);

    DockControlBar(&m_wndColorBar); // 触发断言的代码行

    return 0;
}

问题原因 #

断言失败是因为启用智能停靠模式（CDockingManager::SetDockingMode(DT_SMART)）后，不能再使用旧版MFC的DockControlBar函数。DockControlBar属于传统停靠机制，和新版的CDockingManager管理的智能停靠不兼容，调用后会触发内部断言检查失败。

解决方案 #

1. 移除代码末尾的DockControlBar(&m_wndColorBar)调用
2. 使用新版停靠函数DockPane(&m_wndColorBar)，并将其放到启用智能停靠之前，和其他工具栏的停靠代码放在一起：

修改后的关键代码段：

// 启用停靠并停靠标准栏
m_wndMenuBar.EnableDocking(CBRS_ALIGN_ANY);
m_wndToolBar.EnableDocking(CBRS_ALIGN_ANY);
m_wndColorBar.EnableDocking(CBRS_ALIGN_ANY);

EnableDocking(CBRS_ALIGN_ANY);
DockPane(&m_wndMenuBar);
DockPane(&m_wndToolBar);
DockPane(&m_wndColorBar); // 新增：用DockPane停靠自定义工具栏

// 启用智能停靠（必须在DockPane之后调用）
CDockingManager::SetDockingMode(DT_SMART);
EnableAutoHidePanes(CBRS_ALIGN_ANY);

额外注意事项 #

• 确保m_wndColorBar的类型是CMFCToolBar，而非旧版CToolBar，因为DockPane只支持MFC扩展库的控件类型。
• 如果需要调整工具栏的停靠位置，可以在DockPane后调用SetPaneAlignment等函数设置对齐方式。

内容的提问来源于stack exchange，提问作者Violet