ComboBox in Toolbar - not calling OnSelChanged()

I added a derived ComboBox to a toolbar. The OnSelChanged virtual function is not being called after the dropdown closes up. Am I missing a flag? Is there still no way for MainFrm to be notified when a ComboBox changes?

//.h
class XComboBox: public CXTPControlComboBox
{
public:
    XComboBox(CXTPCommandBars* pCommandBars = NULL);

    // ClassWizard generated virtual function overrides
    //{{AFX_VIRTUAL(XComboBox)
    public:
        virtual void OnSelChanged();
    //}}AFX_VIRTUAL

};

//.cpp
XComboBox::XComboBox(CXTPCommandBars* pCommandBars)
: CXTPControlComboBox(pCommandBars)
{
}

void XComboBox::OnSelChanged()
{
    int index = this->GetCurSel();
    CString text;
    this->GetLBText(index, text);
    AfxMessageBox(text);
}

//MainFrm.cpp
int CMainFrame::OnCreateControl(LPCREATECONTROLSTRUCT lpCreateControl)
{
    if (lpCreateControl->bToolBar)
    {
        if (lpCreateControl->nID == IDC_FONTCOMBO)
        {
            XComboBox* pCB = new XComboBox(GetCommandBars());
            lpCreateControl->pControl = pCB;
            return true;
        }
    }

    return 0;
}