Hello. I have a few groups of widgets that I would like to display in a menu as in the image above. Here's the setting in the documentation:
Controller—Web AppBuilder for ArcGIS (Developer Edition) | ArcGIS for Developers
So, groupSetting=dropDown needs to be added in the config.json, I think. Did you draw the image above, or is it from a real WAB app? If it's in a WAB app, we just need to look at the config.json file. I hope that helps.
EDIT: I see that you already saw that page in the docs. So we just need to figure out how to add it to the config.json. Lame.