Huawei Mate 9 - Manual (Page 45)

Ending recent tasks
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Touch Recent.
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To end a task, swipe it to the left or right or touch the icon in the top-right corner.
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Touch to end all tasks.
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To prevent a task from ending, touch the icon in the top-right corner. This will lock
that task. To unlock a task, touch the icon in the top-right corner.
Screen and Display
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