Hi,
The plugin will definitely work. It’s not dependent on browser.
What may not work with Flock is the CSS generator. I’ve never tried Flock before and I’ve never heard anyone say they’ve used it either. It’s just a variant of Firefox so it should work.
Have you been altering the CSS outputted by the generator? It looks like you’ve added some sort of border to the bottom of your main menu which is messing up the positioning of the flyouts. Perhaps that is causing your problems?