/usr/share/help/cs/gthumb/ is in gthumb-data 3:3.4.3-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/help/cs/gthumb/attributes.page
/usr/share/help/cs/gthumb/batch-change-date.page
/usr/share/help/cs/gthumb/batch-convert-format.page
/usr/share/help/cs/gthumb/batch-resize.page
/usr/share/help/cs/gthumb/batch-rotate.page
/usr/share/help/cs/gthumb/batch-scripts.page
/usr/share/help/cs/gthumb/bookmarks.page
/usr/share/help/cs/gthumb/browser.page
/usr/share/help/cs/gthumb/edit-colors.page
/usr/share/help/cs/gthumb/edit-redeye.page
/usr/share/help/cs/gthumb/edit-resize-crop.page
/usr/share/help/cs/gthumb/edit-rotate.page
/usr/share/help/cs/gthumb/edit-save-undo-redo.page
/usr/share/help/cs/gthumb/extensions.page
/usr/share/help/cs/gthumb/figures/
/usr/share/help/cs/gthumb/figures/comment.png
/usr/share/help/cs/gthumb/figures/general-filter.png
/usr/share/help/cs/gthumb/figures/import-pref-auto-folder.png
/usr/share/help/cs/gthumb/figures/import-pref-custom-format.png
/usr/share/help/cs/gthumb/figures/import.png
/usr/share/help/cs/gthumb/figures/main-win.png
/usr/share/help/cs/gthumb/figures/nav-button.png
/usr/share/help/cs/gthumb/figures/palette.png
/usr/share/help/cs/gthumb/figures/preferences.png
/usr/share/help/cs/gthumb/figures/specific-filter.png
/usr/share/help/cs/gthumb/figures/thumbnail-pane.png
/usr/share/help/cs/gthumb/file-copy-move.page
/usr/share/help/cs/gthumb/filtering.page
/usr/share/help/cs/gthumb/fullscreen.page
/usr/share/help/cs/gthumb/gimp.page
/usr/share/help/cs/gthumb/import.page
/usr/share/help/cs/gthumb/index.page
/usr/share/help/cs/gthumb/introduction.page
/usr/share/help/cs/gthumb/legal.xml
/usr/share/help/cs/gthumb/printing.page
/usr/share/help/cs/gthumb/rename-series.page
/usr/share/help/cs/gthumb/sharing-disc.page
/usr/share/help/cs/gthumb/sharing-social.page
/usr/share/help/cs/gthumb/shortcuts.page
/usr/share/help/cs/gthumb/slideshow.page
/usr/share/help/cs/gthumb/sorting.page
/usr/share/help/cs/gthumb/strftime.page
/usr/share/help/cs/gthumb/thumbnail-pane.page
/usr/share/help/cs/gthumb/thumbnails.page
/usr/share/help/cs/gthumb/viewer.page
/usr/share/help/cs/gthumb/wallpaper.page