Onyx International BOOX Nova2 User Manual page 64

Floating Toolbar Settings
It is enabled by default and can be turned off manually. After disabled, it
can no longer be called out;
It can be customized whether the indicator is displayed after it is
collapsed. Call out the Floating Toolbar by swiping from the screen edges.
The Toolbar's size, display style and functions buttons are customizable.
Custom function buttons support up to 11 in horizontal style and up to 14
in vertical style;
Press and hold the function button icon to display the definition of the
function button;