I would like my Dock to show only the windows of the current workspace. Especially in the little preview window. I find it very confusing to jump around workspaces when trying to find the right window.
Open Terminal and run
gsettings set org.gnome.shell.extensions.dash-to-dock isolate-workspaces true
Here you can see more information about this extension, and also install it: https://extensions.gnome.org/extension/887/workspace-isolated-dash/