> How is Rubberduck supposed to know where to find the XML for the custom UI? I toyed with Ribbon stuff once, and there doesn't seem to be any standard way to do this - you could have your XML inlined in concatenated string literals, or loaded from disk, or pulled from a database.
And then sure you could have an `onAction` callback, but then you could have callbacks to determine visibility of UI elements, or to load a picture, or a description, ...what specific XML attributes in what specific