How does the Nubian Z9 mini Open the Palm lock screen? Z9 Mini Palm Lock screen setting method

1, feel that this phone all the operation is starting from the setting, we click on the desktop "Settings" application icon, and then click the "Personalized Features" option to enter, find "touch gestures", as shown in the following figure:

2, on the phone to open the touch gesture interface we will see a "open", and then our "Palm lock screen" on it, and finally back to the main interface will be placed in the palm of the phone screen only a few seconds to find the phone automatically lock screen, as shown in the following figure:

This function is not very useful, why do you put your hands on it to lock the screen, can not be directly placed on the line or directly wait a few seconds on the good? I believe you know what this is called.