These have the same visual effect and timing than the gnome-shell ones. During the hide animation, the popover has been made to take focus elsewhere, and refuse to take any pointer/keyboard input until the popover is shown again.
This has been based on work from Timm Bäder.
https://bugzilla.gnome.org/show_bug.cgi?id=741405
cff1694 popover: Add show/hide transitions
docs/reference/gtk/gtk3-sections.txt | 2 +
gtk/gtkpopover.c | 307 ++++++++++++++++++++++++++++++++--
gtk/gtkpopover.h | 6 +
3 files changed, 298 insertions(+), 17 deletions(-)
Upstream: git.gnome.org