Shark-Tooth like Moldings for the '65 Formula S Headliner?

I wonder if these pieces that help to stretch the left and right sides of the headliner just screw onto the ceiling or if there is a gasket used or what? Do they go on first, then the headliner, then everything else on top? Thank you.

shark took headliner molding.JPG

Headliner teeth.JPG