How to get the maximum rate (frequency) at which a slider can be moved?

I want to determine the rate (frequency) at which a slider can be moved in a MFC based Visual C++ program (using Visual Studio 2012). So how do I get the appropriate polling rate programmatically?

Here is the code I use for capturing the slider value:

void CMainDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
// catches slider horizontal scrolling events
{
    double val;
    ScopeGuardMutex guard(&m_mutex);
    val = (double)(((CSliderCtrl *)pScrollBar)->GetPos()) / (double)SLD_MAX;
    rec->param = val;
    CDialog::OnHScroll(nSBCode, nPos, pScrollBar);
}

If this value cannot be determined programmatically then is there an approximate value e.g. 100Hz?