I'm making javascript gadget using this page and I need to apply it for my gadget. If you wonder why I don't use API, because it works in wiki where uses captcha for unconfirmed user. So unconfirmed users can't use API for editing with changing content model. And I'm considering to support these users. I need to redirect another page including URL search params when it changes content model like wpExtraQueryRedirect
from submit action of index.php. Please let me know parameters to Special:ChangeContentModel.