Adwaita: menus from menubars should not be rounded
Menus in refreshed Adwaita have rounded corners but with exception for menus opened from menu bar. This exception is broken since (it seems to me) last two releases of GTK3 — shadows are not rounded in that case but background it is rounded. See attached video. It's hard to notice this bug on white background.
Arch Linux, gtk 1:3.24.9-1