Or worse, those UI affordances may change over time. With the swipe down behavior you mentioned, on iOS, I used to just swipe down from the center of the top of

Or worse, those UI affordances may change over time. With the swipe down behavior you mentioned, on iOS, I used to just swipe down from the center of the top of the iPad to see the notification shade. A recent iOS behavior made it so swiping down from the center now causes the app window to be dragged. Ugh! Now I have to relearn to find a spot slightly to the right to pull down to view the shade.