```js
// your-addon-register-file.js

import { useGlobals } from '@storybook/api';
import { AddonPanel, Placeholder, Separator, Source, Spaced, Title } from '@storybook/components';

const ThemePanel = props => {
  const [{ theme: themeName }] = useGlobals();
  const theme = getTheme(themeName);

  return (
    <AddonPanel {...props}>
      {theme ? (
        <Spaced row={3} outer={1}>
          <Title>{theme.name}</Title>
          <p>The full theme object/p>
          <Source code={JSON.stringify(theme, null, 2)} language="js" copyable padded showLineNumbers />
        </Spaced>
      ) : (
        <Placeholder>No theme selected</Placeholder>
      )}
    </AddonPanel>
  );
};
```