Design for tablet of having hardware button.

Features:
* As system navigation bar
* No any extra permission
* Support stylus (Samsung S-pen ASUS Z stylus ...etc)

這個應用程式使用了"協助工具服務"來調用系統的home、back和recent按鈕
除此之外並沒有其他的用途，請安心使用!
This application use the "accessibility service" to call the system home back and recent button.
I don't use it to get extra info. Don't worry about it and the Open source is :
https://github.com/DaxiaK/VirtualSoftKeys