MFC多文档编程时遇到的问题

在MainFrame中使用ON_REGISTERED_MESSAGE(AFX_WM_CHANGE_ACTIVE_TAB, &CMainFrame::OnActivateTabChanged)
//切换视图时触发的响应
LRESULT CMainFrame::OnActivateTabChanged( WPARAM wp,LPARAM lp )
{
int tab =((CMFCBaseTabCtrl*)lp)->GetActiveTab();
if (tab != -1)
{
FreeDlgObjAndWndMemory();
int managerIndex = XJUIGetActiveManagerIndex();
if (m_nActivatedTabView == managerIndex)
return 0;

m_nActivatedTabView = managerIndex;
XJUIGetTree().UpdateFileTree(managerIndex);
}
return 0;
}