If you have sub classed the Activex control with edit box, change
PreCreateWindow
function as follows in
COleControl
derived class,
BOOL CEditActiveXCtrl::PreCreateWindow(CREATESTRUCT& cs)
{
cs.style = cs.style | ES_AUTOHSCROLL | ES_AUTOVSCROLL | ES_MULTILINE;
cs.lpszClass = _T("EDIT");
return COleControl::PreCreateWindow(cs);
}