Do they get sucked out or pushed in on the move, or do they just flap around? I'm going to make some half screens and it would help my design to know what forces will act on them.

If it acts the same as my frogeyed sprite then they get sucked out at speed. HTH

made some half screens went out for about ten miles went up to a ton and seems ok .will try them out to donni but stops a lot of wind
Rescued attachment P1010018.JPG

Aha! The funky air flow characteristics of a Se7en....

When I've driven the 7 in rain when there's lots of spray you can see air / spray that goes to the side of the screen gets sucked into the cockpit quite vigarously (hence spray ending up on the inside of the windscreen).
Also, people have reported difficulty breathing in a 7 cockpit due to negative pressures (relative to atmosphere).

Both things suggest side doors will be sucked in at speed and would only flap forwards under heavy braking if not restrained.