I have abandoned modifying $:/core/macros/tag-picker and found I can reengineer the editor toolbar link dropdown to achieve what I want. As soon as I did so it took me minutes to make additional editor and view Toolbar buttons.
- So I will consider this as solved by myself !
- See https://sandbox-by-tones.tiddlyhost.com my sandbox for examples of how useful a Tiddler Picker is.