Here's a dumb question...
I'm installing some used windows that didn't come with screws. Thanks for the info on the correct type of screws.

My question is: Do the screws just grab the side of the groove/channel, or do they penetrate the groove for extra holding power? The groove is so shallow that I can't imagine that option 'A' above is correct, but I thought I'd check to be sure.
If 'B' is the correct option, I'm guessing that it would be helpful to line up the trim ring and window on a work bench and drill pilot holes???
Thanks for any tips...