MFC Feature Pack for Visual C++ 2008的BUG之一

CMFCTabCtrl::EnableActiveTabCloseButton

用于在CMFCTabCtrl的Tab页显示一个关闭按钮，看看关闭按钮怎么实现：

void CMFCBaseTabCtrl::OnLButtonDown(UINT nFlags, CPoint point)

{

m_bWindowPosChanged = FALSE;

CWnd::OnLButtonDown(nFlags, point);

if (m_rectCloseButton.PtInRect(point))

{

m_bTabCloseButtonPressed = TRUE;

RedrawWindow(m_rectCloseButton);

return;

}

...

void CMFCBaseTabCtrl::OnLButtonUp(UINT nFlags, CPoint point)

{

if (m_bTabCloseButtonPressed)

{

m_bTabCloseButtonPressed = FALSE;

m_bTabCloseButtonHighlighted = FALSE;

RedrawWindow(m_rectCloseButton);

if (m_rectCloseButton.PtInRect(point))

{

CWnd* pWndActive = GetActiveWnd();

if (pWndActive != NULL)

{

pWndActive->SendMessage(WM_CLOSE);

}

return;

}

}

...

应该就这些了。

在例子TabbedView中添加这个功能：

int CTabbedViewView::OnCreate(LPCREATESTRUCT lpCreateStruct)

{

if (CTabView::OnCreate(lpCreateStruct) == -1)

return -1;

AddView (RUNTIME_CLASS (CView1), _T("Simple"), 100);

AddView (RUNTIME_CLASS (CView2), _T("List"), 101);

AddView (RUNTIME_CLASS (CView3), _T("Form"), 102);

AddView (RUNTIME_CLASS (CView4), _T("ScrollView"), 102);

m_wndTabs.EnableActiveTabCloseButton();

return 0;

}

然后点击一个页面上的关闭按钮，会发现这个tab页并没有消失，而切换到其他页面，程序就中断了，问题出在：

BOOL CMFCTabCtrl::SetActiveTab(int iTab)

{

...

if (m_iActiveTab != -1 && m_bHideInactiveWnd)

{

//--------------------

// Hide active window:

//--------------------

CWnd* pWndActive = GetActiveWnd();

if (pWndActive != NULL)

{

pWndActive->ShowWindow(SW_HIDE);

}

}

由于窗口已经销毁，而该Tab页仍然存在，所以m_iActiveTab就是被销毁的窗口所在页面，pWndActive是已经被销毁的窗口，自然调用其ShowWindow方法就出错了。