Timm Bäder authored Aug 10, 2016 and Matthias Clasen committed Aug 16, 2016

The effect of transitions-enabled=true can now be
achieved using gtk_popover_popup/popdown and the effect
of transitions-enabled=false can be achieved using
gtk_widget_show/hide.

https://bugzilla.gnome.org/show_bug.cgi?id=769706