Android Lollipop introduced screen pinning: a way for you to lock your device into one app until a specific shortcut was tapped to take you out of it and let you switch to something else.

In Lollipop, a screen is pinned by going to Recents and tapping the green pin button at the bottom right of any app card, and it is unpinned in one of two ways: short tapping Recents and Back simultaneously if no Accessibility service is enabled in your Settings at all, or long tapping Recents if at least one Accessibility service is switched on. That created several problems:

  • the confusion over which shortcut to use depending on whether you have some Accessibility service enabled,
  • the automatic switch to Recents each time you unpinned (you were pressing Recents after all...), which meant that you had to tap the app again to go back to using it,
  • and more recently, the conflict with Multi-Window on N, which requires the same long-tap on Recents action to get triggered.

That latter part is probably why the unpinning shortcut was changed in Android N. Now, all you have to do is long tap on Back, regardless of whether some Accessibility service is enabled or not. Nice, eh? Even better, you're not pressing Recents at any point, so it no longer throws you back into the Recents screen. To quote Artem's reaction: "Hallefuckinglujah."

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Screen pinning and toast message for screen unpinning (with accessibility services off).

There is one bug with this change though. When an accessibility service is enabled, the screens that explain the feature and the toast error message haven't been completely updated. The green overlay that shows up when you first pin a screen has its text changed, but the back button isn't highlighted in the navigation bar. And even though you will need to tap and hold Back to unpin, your N phone will tell you to tap and hold Recents Overview.

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With an accessibility service turned on, the Back button isn't highlighted in the green box and the toast message incorrectly tells you to tap Overview instead of Back.

Artem has filed a bug on the AOSP tracker to notify the team of these two glitches. As it stands, they're only going to confuse anyone with some Accessibility service turned on, like they did with the original Android Police commenter who brought this change to our attention.