So this is a Multiview Editor, with a Visual Library implementation in the Visual view and a palette in the Source view. To generate the code needed for this infrastructure, I needed to set the following options, first in the New Window component wizard:
And then in the New File Type wizard:
After completing these two wizards, my module contained all the classes below (as well as many new entries in the layer.xml and project.xml files) and I needed to perform no extra steps, no tweaking of the code, nothing at all:
The Multiview Editor that is created is not an implementation of the XML MultiView Editor API. It uses the 'old' Multiview Editor API. For XML files, the XML MultiView Editor API should be included in these wizards, with additional panels for analyzing the XML and deriving editor sections, followed by design choices and a visual library implementation for laying out the visual view... those are some of the areas to work on when extending this scenario to create a complete XML Visual Editor Generator.