Pointer Location issue under Ubuntu 18.04
Under Ubuntu 18.04 on a Dell XPS 15 9560 setting this ON makes the Control key behave strangely. Specifically, it will "unfocus" current field while holding it as if Escape was pressed. My issue was centered around editing CSS in a browser's Developer Console, as when I tried to control+C for Copying the selected text would unfocus, thus not letting me copy the selected HTML/CSS rule/value. After much testing, I found the issue was in the ~/.config/dconf/user file, where the gnome-tweak's configuration is saved.
I asked a question on askubuntu, that I answered myself: https://askubuntu.com/questions/1075160/strange-behaviour-of-the-ctrl-keys-under-x-on-ubuntu-18-04-dell-xps-15-9560/1077478#1077478