$schemamarkup = get_post_meta(get_the_ID(), 'schemamarkup', true); if(!empty($schemamarkup)) { echo $schemamarkup; }

How to Setup Trackball Scroll on Gnu/Linux Distros

GNU/Linux Trackball Scroll Setup – Step-by-step Guide

The tutorial shows you step-by-step How to Manually Enable the Trackball Scroll in GNU/Linux desktops – Step by step Tutorials.

And the Trackball Scroll on Linux is here enabled with the Click Button & Move gesture.

Especially relevant: the Linux Trackball Scroll Setup is making use of the evdev Generic Input Event Interface XOrg Driver.

How to Setup Trackball Scroll on GNU/Linux Distros

GNU/Linux Trackball Scroll Wheel Emulation Guides