If you press back when you're as far back in the app as possible, you'd get a notification (vibration, LED flash, beep). Press back one more time (or twice) and you'd leave the app to whatever app you were on earlier.
:set noerrorbells novisualbell
Don't flash, blink buzz or beep at me when nothing is wrong. Grr.
Perhaps, but when you try to scroll past the end of a list in Android (at least in the ROM I'm using) you get a bounce and a horizontal line indicating that you're at the end of a list and can go no further. That's more what I had in mind.
:set noerrorbells novisualbell
Don't flash, blink buzz or beep at me when nothing is wrong. Grr.