| "Yes, prior to Blockly v8 everything was just one big Blockly object. In
v8 things are modularized so when you reassign Blockly.Blocks, that
means the Block class is no longer looking at the same object as what
you reassigned to"
ah right got it, so mutate the blocks object rather than replace it.... sorry of course it doesn't say in the docs you can just replace the Blocks object with a modified one, I just made that up... because I have > 50 blocks, and also the linter I use gets annoyed that I use array syntax instead of object :-)
the object.assign approach works out fine, all back on track.
I like the new (as yet undocumented API) though, it's nicer to have, I will switch to it when it's ready.
thanks to all