Prevent submitting from another frame

[Danny & Noemi Shafir]

Hi all,

I'm doing a manipulation with frames in the following way:
I have 2 frames in a window: a main frame and an invisible
frame. every time I want to do some calculations on the data
in the server side, I submit the invisible frame's form, doing stuff on
the server, and giving back answers as orders in javascript. those
orders tell the main frame what to do...

but I have a problem:
I want to check the main nad upper frame's data BEFORE submitting it in
the SERVER side. So, I tried (on onClick of the submit button in the
main frame) to call a function on the invisible frame, submitting it,
then do thing on the server, and get an answer.
NOW, how can I prevent the main frame from continuing to the
next page?

Thanks a lot,
Danny