pref_category_reader_key
pref_category_accounts_key
pref_category_downloads_key
pref_default_viewer_key
pref_hide_status_bar_key
pref_lock_orientation_key
pref_enable_transitions_key
pref_show_page_number_key
pref_keep_screen_on_key
pref_custom_brightness_key
pref_custom_brightness_value_key
pref_download_directory_key
pref_download_threads_key