Nested categories

Categories may be nested within other categories. Here are two top-level categories ('Core' and 'Custom'), the second of which contains two sub-categories, each of which contain blocks:

Note that it is possible for a category to contain both sub-categories and blocks. In the above example, 'Custom' has two sub-categories ('Move' and 'Turn'), as well as a block of its own ('start').

JSON

{
  "kind": "categoryToolbox",
  "contents": [
    {
      "kind": "category",
      "name": "Core",
      "contents": [
        {
          "kind": "block",
          "type": "controls_if"
        },
        {
          "kind": "block",
          "type": "logic_compare"
        },
      ]
    },
    {
      "kind": "category",
      "name": "Custom",
      "contents": [
        {
          "kind": "block",
          "type": "start"
        },
        {
          "kind": "category",
          "name": "Move",
          "contents": [
            {
              "kind": "block",
              "type": "move_forward"
            }
          ]
        },
        {
          "kind": "category",
          "name": "Turn",
          "contents": [
            {
              "kind": "block",
              "type": "turn_left"
            }
          ]
        }
      ]
    }
  ]
}

XML

<xml id="toolbox" style="display: none">
  <category name="Core">
    <block type="controls_if"></block>
    <block type="logic_compare"></block>
  </category>
  <category name="Custom">
    <block type="start"></block>
    <category name="Move">
      <block type="move_forward"></block>
    </category>
    <category name="Turn">
      <block type="turn_left"></block>
    </category>
  </category>
</xml>