In this case, the fact that you can set the framerate to '30', but then can't place a 30 FPS clip on the timeline because the actual framerate on the timeline is 29.97 is just unreal. (Yes, I've tried ignoring the message -- the clip is jerky or just goes green). I've looked through the explanations in past forum posts and can just about follow the twisted logic of it, but I'm sorry, it beggars belief that anyone accepts or ever accepted this as a feature of any piece of software. It should never have been released without some kind of feature that automatically smooths over minor framerate differences. Hell, no one should have to even think about framerate until they're at the stage of exporting the video project.
I give up. Trying to make videos shouldn't make you feel like someone is deliberately trying to drive you insane.