Feature Idea: simple and advanced mode

The new Blockly is brilliant. There are some really nice Python features you have surfaced into blocks.

However, there are a lot of palettes and a lot of blocks, and it looks a bit overwhelming as a starters language the first time you try it.

Would it be possible to have a beginners and an advanced mode? Where beginners mode contains a smaller number of palettes and blocks to get people started, but then the advanced mode adds all the other ones in?

I'm not sure yet how we would choose the subset that goes into beginners mode - perhaps watch some children using the editor for the first time and see which blocks they use, and base it on that? Or look at a representative base of existing python resources coded into blocks, and only include the blocks required to implement those resources?

No files or tests are named. Start by locating where the editor defines its palettes and blocks, then determine how a beginner subset and the switch to advanced mode should be selected. Done means the two modes are implemented with an agreed block subset and the editor clearly exposes the transition between them.

Written by the indexing model from the issue text.