Very funny.
If I read the manual for everything I've ever used, I'm not sure I'd have time to actually accomplish anything in the end.
Sure, let me spend a day reading through the lists of keyboard/mouse shortcuts for every piece of software I use just to see if there's anything useful in there? No thanks...
Good UX would pop up a balloon informing me of the feature after the first time I held down my left-arrow key for more than, say, keypresses.