Delayed activation of Quaternion window after notification
Perhaps related to the discussion in 4ba85fd1. When a Quaternion notification occurs, there is no button to click to activate its window, and clicking on the notification simply makes it disappear.
However, if a notification for VLC occurs next (with libnotify enabled, see #77 (comment 64144)), and the next or previous button is clicked, then the Quaternion window is activated (I assume this is not specific to VLC, but I haven't tested it with anything else).
This only happens once after each new Quaternion notification, so it seems that a pending activation is consumed at that point.
Perhaps there is a bug in Quaternion as mentioned in 4ba85fd1, however there may also be something to fix in xfce4-notifyd in this case.