MFC Tabbed Documents - how to enable middle-mouse button to close document?

Answer 1

No subclassing needed (phew). Managed to get it working by hijacking the PreTranslateMessage of the mainframe. If the current message is a middle-mouse-button message, I check the location of the click. If it was on a tab then I close that tab.

BOOL CMainFrame::PreTranslateMessage(MSG* pMsg)
{
    switch (pMsg->message)
    {
     case WM_MBUTTONDBLCLK:
     case WM_MBUTTONDOWN:
     {
      //clicked middle button somewhere in the mainframe.
      //was it on a tab group of the MDI tab area?
      CWnd* pWnd = FromHandle(pMsg->hwnd);
      CMFCTabCtrl* tabGroup = dynamic_cast<CMFCTabCtrl*>(pWnd);
      if (tabGroup)
      {
       //clicked middle button on a tab group.
       //was it on a tab?
       CPoint clickLocation = pMsg->pt;
       tabGroup->ScreenToClient(&clickLocation);
       int tabIndex = tabGroup->GetTabFromPoint(clickLocation);
       if (tabIndex != -1)
       {
        //clicked middle button on a tab.
        //send a WM_CLOSE message to it
        CWnd* pTab = tabGroup->GetTabWnd(tabIndex);
        if (pTab)
        {
         pTab->SendMessage(WM_CLOSE, 0, 0);
        }
       }
      }
      break;
     }
     default:
     {
      break;
     }
    }
    return CMDIFrameWndEx::PreTranslateMessage(pMsg);
}