I had to look around for the switch to turn off hot corners in Gnome. You know, this little annoying thing that will show the the applications overview and icon-bar. In older gnome versions you may have switches on the top level of the gnome-tweak-tool or some gnome extensions dedicated to that problem. But in the actual version, you may not find the buttons and most of the extensions won’t work. Here ist he way to find the option right now. Just for the record, the Gnome version in Fedora28:
$ gnome-shell –version
GNOME Shell 3.28.3
Still with the tweak tool you can switch off the hot corners. So install it, if not done yet:
$ sudo dnf install gnome-tweak-tool
And start it with:
Go to extensions -> Activitys configurator -> klick on the config-wheel -> diable hot corners.