Preserve center of view when zooming in 1up.  See https://bugs.edge.launchpad.net/gnubook/+bug/402262
Preserve center of view when zooming in 1up.  See https://bugs.edge.launchpad.net/gnubook/+bug/402262

gootdude/bookreader,gootdude/bookreader,brisandbeans/bookreader,niksu/bookreader,brisandbeans/bookreader,Islandora/internet_archive_bookreader,yankl/bookreader,Islandora/internet_archive_bookreader,nikolas/bookreader,niksu/bookreader,internetarchive/bookreader,Islandora/internet_archive_bookreader,openlibrary/bookreader,garyrh/bookreader,openlibrary/bookreader,openlibrary/bookreader,gootdude/bookreader,openlibrary/bookreader,niksu/bookreader,yankl/bookreader,brisandbeans/bookreader,yankl/bookreader,brisandbeans/bookreader,openlibrary/bookreader,garyrh/bookreader,yankl/bookreader,nikolas/bookreader,Islandora/internet_archive_bookreader,brisandbeans/bookreader,gootdude/bookreader,niksu/bookreader,internetarchive/bookreader,yankl/bookreader,Islandora/internet_archive_bookreader,garyrh/bookreader,garyrh/bookreader,garyrh/bookreader,niksu/bookreader