Sailfish is also based on gesture navigation. The home screen shows large icons of running apps, and with a swipe from the left users can access a screen that aggregates messages and some settings. To get back to the home screen from an app users just have to swipe from either side. It's a pretty easy concept to grasp even if you haven't used the platform before.
There is no doubt that Jolla and Ubuntu as well as Samsung and Mozilla face massive challenges. Windows Phone's struggles have shown how difficult it is to compete with Android and iOS even if you have massive resources.
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