b121c25184
MessageTray tweens both opacity and y to hide or show _notificationWidget, but only y when expanding it. This means that an existing tween to hide the notification will continue running, clearing the notification state. If the hiding one completes before the showing one, the onComplete handler will throw an exception (because the notification was nullified) and therefore break the state tracking. https://bugzilla.gnome.org/show_bug.cgi?id=683986