As part of the desktop refresh project, Vector will soon no longer run the SkinTemplateOutputPageBeforeExec hook.
Impacted projects:
# modifying footer
* Wikimediamessages https://gerrit.wikimedia.org/g/mediawiki/extensions/WikimediaMessages/+/33217b8036059ee817b169f59f8d78726a4ed852/includes/WikimediaMessagesHooks.php#229
# modifying languages
* https://github.com/wikimedia/mediawiki-extensions-Wikibase/blob/fafca1f24bfab9e7e0419f1d9a43503a66b5adb0/client/includes/Hooks/SkinTemplateOutputPageBeforeExecHandler.php#L52 (modifies language_urls).
* https://gerrit.wikimedia.org/g/mediawiki/extensions/UniversalLanguageSelector/+/18552a71428f46d0ba6a955c6679b2f0965c0ca0/includes/UniversalLanguageSelectorHooks.php#426 (also modifies language_urls)
# side bar
* LanguageSelector modifies side bar (https://gerrit.wikimedia.org/g/mediawiki/extensions/LanguageSelector/+/8e3c6d6c8a17170b103f7de2f1ee4b5f2b2be111/LanguageSelector.php#299)
Third parties:
# modifying feeds
* News (modifies feeds https://gerrit.wikimedia.org/g/mediawiki/extensions/News/+/18480933ba03da21b4596fa006830b801a244a64/News.php#112)
# modifying languages
* https://gerrit.wikimedia.org/g/mediawiki/extensions/StickToThatLanguage/+/896663af81498ddb5e7f7d01c50edcc0c245ad9e/StickToThatLanguage.hooks.php#79
# modifying categories
* BlogPage https://gerrit.wikimedia.org/g/mediawiki/extensions/BlogPage/+/ea18eb7cf03321e912c89e975fef766417bcb851/includes/BlogPage.hooks.php#29
## adding footer items
* https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/PushToWatch/+/master/PushToWatch.class.php
* https://gerrit.wikimedia.org/g/mediawiki/extensions/Wikidata.org/+/32193c6100734e27a4b525d795ae85da2af4c954/src/Hooks.php#53 (adds footer link)
* WhoIsWatching https://gerrit.wikimedia.org/g/mediawiki/extensions/WhoIsWatching/+/7e4ac0dee460de88aaeebd0da078820ee7929d44/src/Hook.php#42
## modifying copyright
* SharedHelpPages (modifies copyright) https://gerrit.wikimedia.org/g/mediawiki/extensions/SharedHelpPages/+/cc4801a5fbc2a7f4476e108ba19a584bd0eabf83/SharedHelpPages.hooks.php#236 Recommendation: TBC
To check:
* https://github.com/SemanticMediaWiki/SemanticBreadcrumbLinks/blob/master/src/HookRegistry.php#L102 does SemanticMediaWiki use Vector?