I'm installing a ceiling in a shower where the contractors left it unfinished. From reading, it sounds like drywall as a shower ceiling can be fine if it's properly primed and painted. Here's my question, though-- the ceiling has a hole cut in it for a light, and that hole obviously has an exposed drywall edge that won't be sealed with the primer or paint. Is that OK, or do I have to somehow get the primer and paint inside the edge of that hole? Thanks!