file_uploader.css, resource_list.css, resource_update.css, resource_view.css, and resource_view_header.css. I did not have any outdated templates before the install. If I try to merge the changes, I get a message telling me that no previous version of the parent could be found, and that merging is not possible.
I mentioned this to the style developer Arty, who thinks it's a bug in XenForo:
When you install add-on or update XenForo it sets last modification time for those templates to time of add-on installation / XF upgrade. Template in style was edited a while ago so it has lower last modification time and XF thinks its outdated.