Can we put things into the workspace dynamically?

[youralien]

Seems like this demo shows you can
https://blockly-demo.appspot.com/static/demos/custom-fields/turtle/index.html

The dynamic changes to the blockly workspace happen here:
https://github.com/google/blockly/blob/master/demos/custom-fields/turtle/index.html

And a bonus -- creating a custom block with a comment happens here!
https://github.com/google/blockly/blob/master/demos/custom-fields/turtle/blocks.js#L20