Hmm, okay. Maybe I'm missing something, but what I was looking for is to make todo lists without each item being a tiddler tagged with a specific tag.
I would like to create a simple list of items which I can prefix with '[ ]' turning them into a checklist. Then if I check one of these boxes, have the contents of the tiddler rewritten to '[X]' which renders as a checked checkbox.
I looked into the built-in checkbox, but it seems to require you to write '<<checkbox>>' and an expression that selects tiddlers as items. Can what I need be done with the built-in checkbox? If not, how can I add the old behavior into tiddlywiki5?