This patch modifies MessageTray behaviour so that normal (not urgent)
notifications are not shown when the user is Busy (they're sent
immediately to the Summary area). When status is then changed,
notifications still pending are shown again.
Additionally, when status is modified from Idle to anything other than
Busy, the message tray is forced open for 4 seconds, so that summary
icons are visible.
https://bugzilla.gnome.org/show_bug.cgi?id=617225
1496c85bb6