Partial fix for high res displays
Summary:
On high res displays we end up using
the tile manager on single pages, that doesn't work
(for reasons that aren't yet clear) - but it
doesn't make sense if we most of the page anyway.
BUG: 401339
Reviewers: Okular, aacid
Subscribers: okular-devel
Tags: Okular
Differential Revision: https://phabricator.kde.org/D20882