I've never seen a foul called when you dropped the cueball while you had ball in hand, it's only a live ball if you touched another ball with it. What if you dropped it on the floor because your grip slipped or the other player tossed it to you? Ball off playing surface is a foul just like dropping into a pocket. To call a foul if you drop the cueball in a pocket in a ball in hand situation would then equal calling a foul if you dropped it on the floor or if you put it down on the table, then moved it again to line up another shot or adjusted it before shooting. To call the foul would mean the cueball was a live ball from the time it left your hand. It's not a live ball till you shoot it. You can place it, aim, then get up and move it again. Only if you hit another ball or strike it with a stoke does it become a live ball in a game. Till then it's like chalk, drop it, juggle it, stick it in your pants, all good. Up until you shoot or foul by moving another ball with it. That moving another ball foul is not because you moved the cueball but because you moved the other ball while not in the middle of a shot, same thing if you dropped your chalk on a ball. Cue ball fouls only apply to things during a shot, not because you are clumsy.