There are a series of simple keyboard shortcuts within the visualiser that work while it's in full screen mode. I'm sat in front of my work PC at the mo (
sans iTunes
) and I can't remember off the top of my head what they are, but if you put your visualiser on full screen and press each letter key in turn, you will see some of them do have an effect - you can manually modify the effects (each visualiser effect is made of three elements, each of which is independently switchable), cap the frame rate, force the track title to remain on/off permanently, etc. One of the keys displays a basic menu of available commands - again, can't remember which, but it may just be 'H'. Experiment with it, that's how I found out what they do. None of the letter keys can damage it in any way, so you can thrash your keyboard in safety.
HTH
