CMFCTabCtrl catch tab change event

Question

I want to catch the tab change event of a CMFCTabCtrl. Below is the code I'm trying to do that. But it does not catch the change event.

BOOL SurvChatDlg::OnNotify( WPARAM wParam, LPARAM lParam, LRESULT* 
                               pResult ) 
{ 
if(((LPNMHDR)lParam)->code==TCN_SELCHANGE) 
{ 
    int i = m_TabControl.GetActiveTab();
    AfxMessageBox("Changed");
} 
return CDialog::OnNotify( wParam, lParam, pResult ); 
}

Answer 1

According to this forum thread, you need to handle the AFX_WM_CHANGING_ACTIVE_TAB message sent to the parent window.

This forum thread has more code samples.

Answer 2

If you want to catch the post tab change, the tab that will be active, need AFX_WM_CHANGE_ACTIVE_TAB ie;

ON_REGISTERED_MESSAGE(AFX_WM_CHANGE_ACTIVE_TAB,OnTabSetActive)

LRESULT CYourClass::OnTabSetActive(WPARAM wParam, LPARAM lParam)
{
    const int iActiveTab = (int)wParam;
    int iCheckActiveTab = m_wndTabs.GetActiveTab(); //CMFCTabCtrl m_wndTabs;
    m_wndTabs.SetActiveTab(iActiveTab); //good idea to also add this depending on usage.
    return 0;
}

And if you require manually changing the tab call using;

    SendMessage(AFX_WM_CHANGE_ACTIVE_TAB, iTabNum2ChangeTo, 0);

Posted the above after trying to find a solution to my problem where using

CMFCTabCtrl::SetActiveTab() 

would crash but in debug mode only. And this OP was googles top answer.

AFX_WM_CHANGING_ACTIVE_TAB appears to catch the event prior to the actual tab change, hence why hasn't worked for the OP, and can be checked by;

int iCheckActiveTab = m_wndTabs.GetActiveTab();