I'm going to show you an effect that you'll recognise immediately, perhaps without ever having paid it much attention. Take any collection of elements that react to hover: a list of menu items, swatches in a colour picker, squares in a grid. Now quickly swipe your cursor across them: In real life, your hand moves across your desk, or your finger across the screen, in a continuous, unbroken motion. But this isn't reflected in the example above. Here, lights in the path of motion are switched on..