Original Bug title:
Provide an API to activate VE on arbitrary textareas for Gadgets and user scripts and document it at [[:mw:VisualEditor/API]]
Please also create a mailing-list for those API updates.
Since users will not be able to understand Wiki-Markup, please provide and API for turning-on VisualEditor on <textarea>s. Example use case would be the Translate Extension where translators still have to enter wiki-markup or LiquidThreads or whatever is adding Wiki-Markup to a page.
Providing an API to Gadget authors and other tools is an important matter; nearly all edits are made through gadgets at certain pages; thus it is not just an "enhancement".