I've done absolutely no research into this, so I don't know how silly a question this is...

I know that iDVD and and all the others have templates and the like for menus and such. How flexible are they? Can you create your own animated menus completely from scratch? What sort of control do you have over the background image, button placement and shape, etc.?

I should look into this further, but most reviews do not seem to care about this. They just brag about the number of stock transitions and menu layouts.