Try it with a scrolling list. The unlock button activates as soon as you press down on it. I was having the same results and didn't really believe his claim until I tried it elsewhere in the OS. 0.5 cm seems about right.
Anyone here familiar with Android's source code and can figure out where this behavior takes place? I'm curious if it can be easily disabled (if only to see what it's like).
ScrollView views use this value internally to prevent accidental scrolling when tapping elements. You can change the touch behavior by subclassing ScrollView (or ListView) and overriding onTouchEvent() to ignore slop and start scrolling immediately on a drag event.
Incidentally, I can't stand most iPhone apps because of their over-sensitivity to scrolling (and their tiny list elements). I'm glad Android has these defaults.
