I am installing a new windshield and when I put the eyebrows on I had a hard time to understand what they physically do? I read somewhere that they are supposed to keep water out to avoid rusting up underneath the corner of glass at the dash panel. But they don't sit tight enough on the glass to keep all water that runs down the glass or along the molding from getting under the eyebrow. Can't believe they would be on there without a purpose? Is it maybe more about keeping leaves and other debris from collecting?