Huawei MediaPad M2 10.1 (M2-A01L) - Manual (Page 8)

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Eraser
 When drawing, press and hold the eraser button to delete
pictures.
Not all apps support this function.
Function button
 Press and hold and then outline the screenshot area to
take a screenshot.
 Press and hold and then double touch the screen to take
a full screenshot.
 Press and hold, and touch the screen to easily open the
floating window for special apps.