Get the control site property specified by the dispIdMember, or <code>null</code> if the dispId is not recognised.
@param dispId the dispId
@return the property value or <code>null</code>
@since 2.1
See Implementation
Get the control site property specified by the dispIdMember, or <code>null</code> if the dispId is not recognised.
@param dispId the dispId
@return the property value or <code>null</code>
@since 2.1