The MATE desktop is not part of the official stock Slackware. I have been quietly using MATE on Slackware since version 1.8 and am now using 1.12. I have no complaints about the appreciated efforts of the maintainers, but when I compared MATE on Slackware to other distros I found something lacking.
MATE never looked right on my Slackware 14.1 system. I decided the difference was missing themes, help files, and caja-actions, which in my use case is indispensable because because Caja does not support direct editing of certain mimetypes, such as *.desktop files.
Fortunately, I am able to fill the gaps of Slackware MATE.
To furnish help files I needed to build webkit-gtk3, which on my dual core system with 8 GB of RAM required about five hours to compile. Five hours is a long time and motivates exclamations such as POS and WTF. With webkit-gtk3 compiled I then could rebuild affected MATE packages as well as build the MATE User Guide, which is part of the Slackware MATE Testing branch.
While I understand the Slackware MATE maintainers avoiding the building of help files because of webkit-gtk3, I think those packages should still be provided and be part of the build tree, albeit with a compile time option to build or ignore.
From slackbuilds.org I built the clearlooks-phenix and clearlooks-classic packages, as well as the gnome-colors and gnome-mime-data packages.
Of course, there were many dependency packages I needed to compile as well.
There was an annoying absence of AisleRiot Solitaire. I consider this game a staple of any desktop. Just because. I found build scripts with the Microlinux project and Salix repos.
Too bad Slackware lacks GUI admin tools.