Facebook will follow its F8 developers conference this Wednesday with another 8-hour "hackathon" for third-party developers and Facebook engineers to work on widgets. This will be fun to watch, because those two groups kind of despise each other right now. Last spring, Facebook began taking a hardline stance against widgets that spam users or violate privacy rules, even going so far as to temporarily remove popular apps like Top Friends and Super Wall from the site this summer. Then, a beta test of Facebook's new profile revealed a new feature that made Slide's Top Friends redundant. Slide responded cheerfully to the news, but one exec at a widgetmaker told us that if Facebook keeps up the regime of enforcement and copycat apps, venture capital for Facebook-focused startups will dry up. Of course, we hardly expect a brawl or even public arguments during the "hackathon" — passive-aggressive Twitter notes and other forms of repressed resentments, anyone? Developers, save yourselves the future therapy bills. Just do what Facebook wants and build the kind of apps its employees describe in the video below. That seems easier.