@davidfor: Not by design, of course

. It's been my experience that people unfamiliar with ereaders tend to try to touch the screen in various ways, which was fun on a K4 (no touchscreen ^^), but is less so when some gestures mess with settings, be it light or font size

.
I tend to stick with a specific brightness, so I know what to go back to, and since I mostly stick with it, the gesture is more of an annoyance to
me 
. I'd be much happier with the harder-to-accidentally trigger two finger one from the Aura, for instance (but then again, I'd be much happier with a capacitive touchscreen, period, so ^^).
Yup, I quite liked the chapter jump gesture on Kindles too, but I kind of understand the reasoning behind killing it (which really was: people complained it was far too easy to trigger accidentally).