In GNOME 3.4, the recent documents search provider which was
available
in 3.2 was removed and replaced by documents search, which is a subset
of tracker's search and shows only documents.
... and gnome-documents only knows about things under ~/Downloads, ~/Documents
and your online accounts. So if you have your PDF in any location that is not
one of these, it will not show up.
Cheers,
Debarshi
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http://i.imgur.com/Z7jjX.jpg