a8b457b52e
PopupMenu needs special-treatment of certain types of menu items, which it determines via children's _delegate property. However as the calendar drop-down is very unmenu-ish, we use regular actors rather than PopupMenuItems and the missing _delegate property triggers a warning. Just add it as the bare minimum to make PopupMenu happy. https://bugzilla.gnome.org/show_bug.cgi?id=781471