No animation on Gtk .Button::activate with GTK 4

With this code I would hope that clicking on the button labelled “Click” will cause the button labelled “Animated” to be animated. This works for me with GTK 3 (just replace 4.0 with 3.0) but not with GTK 4.

import gi
gi.require_version("Gtk", "4.0")
from gi.repository import GLib, Gtk

win = Gtk.Dialog()
click = win.add_button("Click", 0)
animated = win.add_button("Animated", 1)
click.connect("clicked", lambda x: animated.emit("activate"))
loop =, False)


GTK 4.0.3 and 4.2.0
Wayland GNOME 3.38

I’ve filed for this