Extension:WikimediaIncubator

This extension adds functions meant for the Wikimedia Incubator, namely:
 * A preference where you can enter the test wiki you are working on
 * 'Project' can be entered, for users who do maintenance and are not working on a test wiki
 * Default is 'None' and emptying it submits 'None'
 * A special page "Special:ViewUserLang" to view the language and test wiki preference of a user
 * Special:RecentChanges displays edits on the user's wiki test
 * 'Project' for all edits except on test wikis
 * 'None' for normal display
 * A magic word that returns the user's wiki test
 * When editing a page, check if the page is prefixed (if in the right namespace, and if the user didn't submit "Project" as preference
 * In that case, show an error message (and suggestion for prefixed title)

Source code
See Toolserver.