Hi,
i am not saying about all information, actually secondary window have some restrictions
you can not use a table in a secondary window, because tables line items are dynamic,
and you can't control its flow in case of secondary windows, so it is prefffered to use
main window, if you wants your smartforms to be more readable and flexible,
then you have to use main window.
Secondary windows are mainly used where you have fixed set of data, in terms of width
height, length, etc, i.e for showing smartform current page, total no of pages, addresses
etc.