Steve Troughton-Smith, a well-known software developer, has discovered a hidden feature in iOS that lets users convert the operating system’s built-in keyboard into a one-handed alternative. Troughton-Smith says the feature has been bundled with Apple’s mobile operating system since iOS 8, which debuted in 2014, but was never actually publicized as an option to iOS users by Apple.

Troughton-Smith revealed the existence of the keyboard in a series of tweets on Wednesday and published a video showing the feature in action. After swiping right to left on the keyboard a couple of times, Troughton-Smith revealed a narrower iOS virtual keyboard that moved to the left side of the screen. The developer says the feature effectively turns the keyboard into a one-handed option for those who want to quickly type a message.

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Apple’s (AAPL) iOS has had a virtual keyboard since the first iPhone debuted in 2007. The keyboard covers the entire screen at the bottom of a text-input field and is most effectively used with two hands (or thumbs) rather than one. However, several third-party keyboards are available in Apple’s App Store for one-handed typing, including Word Flow SwiftKey.

https://twitter.com/stroughtonsmith/status/788869300283146240

It’s perhaps no surprise, then, that Apple has apparently thought about adding one-handed typing to its operating system. Exactly why it hasn’t talked about it or made it easily available, however, is unknown.

Those who want to access the single-handed keyboard might have some trouble. According to Troughton-Smith, Apple intentionally hid the feature, and he was only able to access it through a developer console for testing application features, including those that might be unavailable to users.

Non-developers who want to use the feature, he says, must jailbreak the operating system, a process that breaks a number of software restrictions in iOS and gives users full control over the software. Jailbreaking is typically for users who want to install apps that aren’t available in Apple’s App Store that could render the operating system useless if not done properly. So, users should be careful if they decide to try it out.

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It’s unclear whether the feature is a remnant of early testing on Apple’s part or if the company is considering adding it to iOS in the future.

Apple did not immediately respond to a request for comment.