Starting the week of April 5th, the Wikimedia Foundation will begin rolling out changes to the default settings on all projects. Wikimedia Commons is planned to be switched over first, and English and other language Wikipedias, and our sister projects will follow as our development and operations teams are ready.

What will change?
The default MediaWiki skin in all Wikimedia Foundation projects will change from Monobook to Vector, and the editing toolbar will be replaced with the new enhanced editing toolbar with dialogs for inserting links, tables and more. These features will be familiar to users who have chosen to opt-in to the beta that has been available since August 6th, 2009.

Who will be affected by this change?
Anyone using the site anonymously, or logged in users whose settings are set to the current site defaults. Users who are affected by these changes may also have user scripts and styles which may not perform similarly to how they did before the swtich-over, or may not be loaded at all. Also, some gadgets, community-developed features available through the user preferences, may not be compatible with these changes. Users who have enabled those gadgets may experience issues related to these incompatibilities. Fortunately, many of the most popular gadgets have already been adapted to Vector during the beta testing period.

Finally, external tools which use screen-scraping to access content rather than the API may be affected by this change, as the HTML structure of Vector is different in some ways from that of Monobook. If, on the other hand, you have built an application that relies on the MediaWiki API to process content, your application will not be affected by this deployment.

How can users make sure their user scripts, user styles, gadgets and external tools will still work?
By testing them with the new settings, you will be able to verify compatibility and resolve any issues. By clicking the “Try Beta” link at the top of any page, and then opting into the beta, you will have turned on the same settings which will be made default.

Another way to test skin compatability is to append “?useskin=vector” to the end of the URL of a page.
For example, the URL would become to see how the page would look using the Vector skin.

What if users decide they want to return to the previous settings?
When a site is switched over to the new settings, the “Try Beta” link at the top of each page will be replaced with a set of links which will provide more information about what changes have been made and a convenient way to change users settings back to how they were before the switch over.

Naoko Komura and the Wikimedia Foundation User Experience team