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TIA.

Thank you, meanwhile I've inserted:
CXTPNotifyConnection* ptrCalendarConn = m_ctrlCalendar.GetConnection();

ASSERT(ptrCalendarConn);
m_Sink.Advise(ptrCalendarConn, XTP_NC_CALENDARCONTEXTMENU, &CPlannerPreview::OnEvent_Calendar);
m_Sink.Advise(ptrCalendarConn, XTP_NC_CALENDARLBUTTONDBLCLICK, &CPlannerPreview::OnEvent_Calendar);
m_Sink.Advise(ptrCalendarConn, XTP_NC_CALENDARKEYDOWN, &CPlannerPreview::OnEvent_Calendar);
m_Sink.Advise(ptrCalendarConn, XTP_NC_CALENDAR_IS_EVENT_EDIT_OPERATION_DISABLED, &CPlannerPreview::OnEvent_IsEditActionDisabled);

in calendar (into dialog-derived class) init function

and

void CPlannerPreview::OnEvent_Calendar(XTP_NOTIFY_CODE Event, WPARAM wParam, LPARAM lParam)
{
 TRACE( "Do nothing: Event %ld - wParam %ld - lParam %ld\n", (long)Event, (long)wParam, (long)lParam);
}

void CPlannerPreview::OnEvent_IsEditActionDisabled(XTP_NOTIFY_CODE Event, WPARAM wParam, LPARAM lParam)
{
 if ( XTP_NC_CALENDAR_IS_EVENT_EDIT_OPERATION_DISABLED != Event)
 {
  ASSERT(FALSE);
  return;
 }
 XTP_EVENT_EDIT_OPERATION_PARAMS* pOPparams = (XTP_EVENT_EDIT_OPERATION_PARAMS*)wParam;
 BOOL* pbCancel = (BOOL*)lParam;
 ASSERT(pbCancel);

 // check is already canceled/handled
 if ( !pOPparams || !pbCancel || *pbCancel)
 {
  return;
 }
 *pbCancel = TRUE;
}

So no action can be taken.