libinput-gestures failed to start as a desktop application

As I tried to start the libinput-gestures after installation:

libinput-gestures-setup start

It failed

libinput-gestures failed to start as a desktop application.

I ventured through Google, but got not solution.

Until I started to try other touchpad drivers, I saw a similar command I just used when installing libinput gestures:

sudo gpasswd -a $USER input

In order to use libinput gestures, the current user must be added into the input group, but it won't take effect until you run the following command to join the group you've just added yourself to:

newgrp input

The newgrp command is used to change the current group ID during a login session.

The official docs suggested reboot after adding user to input group.

Obviously too long, I didn't read.