After setting "widget.allow-client-side-decoration" to true and restarting firefox, I can see those CSDs even with default Fedora 26 and Fedora 27 builds. See also: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx/thread/XXNOQ6GVGGNNTFGSEUIR3IXURMMRMOJK/ _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx