OK. Thank you. I will try it, though my hope was to figure out why adblock plus wouldn't install.

Message: Must declare JSON Schema v3 version in "$schema".

What must be done?

Those instructions are not for Salix. They are for a distribution that usually splits a single package into hundreds of tiny little pieces for no reason at all.
Thanks. That clarifies it very well for me. It is a byproduct of documentation being for Ubuntu, Mint, Debian or "other distributions ...

This is part of the gtk+2 package, so if you have that installed (you should) you already have it.
Great! Thank you. It's odd that I'd be instructed to install it: http://xfce-look.org/content/show.php/Ambiance+%26+Radiance+Colors+Suite?content=147891
I should have noted that I am using the XFCE ...

A theme I want to use requires the Murrine and Unico engines and "gtk2-engines-pixbuf." I found and compiled Murrine and Unico in Sourcery, but could not find "gtk2-engines-pixbuf" there or in Gslapt. The clearest link I found regarding the file in a web search was this one: http://download.gna.org ...