When launching mate-tweak 18.04.8 the application fails to launch and gives the following error:
(mate-tweak:9397): GLib-GIO-ERROR **: Settings schema 'org.mate.Marco.general' does not contain a key named 'side-by-side-tiling'
Trace/breakpoint trap
This has already been fixed upstream with the release of mate-tweak 18.04.9
https://github.com/ubuntu-mate/mate-tweak/archive/18.04.9.tar.gz