message: Add support for select boxes.
diff: @@ -147,7 +147,7 @@ function ViewWidgetElement(props: {w: WidgetElement; post}) {
  handler: events[k],
  args: { type: 'unit' }
  });
  - } else if (tag === 'input' && attributes.type === 'text' && k === 'onChange') {
  + } else if (((tag === 'input' && attributes.type === 'text') || tag === 'select') && k === 'onChange') {
  new_attrs.onChange = (e) => post({
  command: 'widget_event',
  kind: 'onChange',
  @@ -155,7 +155,7 @@ function ViewWidgetElement(props: {w: WidgetElement; post}) {
  args: { type: 'string', value: e.target.value }
  });
  } else {
  - console.error(`unrecognised event kind ${k}`);
  + throw new Error(`unrecognised event kind ${k} for ${tag}`);
  }
  }
  const vs = children.map(html => ViewHtml({html, post, ...rest}));
  