How to assign a custom icon to a specific subtype.

icon.for.subtype.txt

src/icons/images/mytype.svg:

  The icon image content.

src/icons/icons.css:

  .binf-widgets .myext-mytype {
    background-image: url('images/mytype.svg');
  }

src/icons/icons.js:

  define([
    'css!myext/icons/icons'
  ], function () {
    return [
      {
        equals: { type: 12345 }
      }
    ];
  });

src/myext-extensions.json:

  {
    "csui/utils/nodesprites": {
      "extensions": {
        "myext": [
          "myext/icons/icons"
        ]
      }
    },
    ...
  }