Currently the messagetray opens up everytime the user hits the bottom of the screen.
To avoid this "opening by accident" this patch changes the behaviour so that:
1) It only opens when there is a notification showing or
2) When the user hits the summary area (assuming he wants to interact with it)
Includes fixes from https://bugzilla.gnome.org/show_bug.cgi?id=607244#c17https://bugzilla.gnome.org/show_bug.cgi?id=607244