## The current behavior

The full value of the `key` is very difficult / impossible to find and use in the interface of the React Devtools.

![Kapture 2020-04-22 at 11 47 47](https://user-images.githubusercontent.com/1935696/79997715-25222680-84ba-11ea-97ba-51f1679a8c91.gif)

Only managed to find it by accident :(

## The expected behavior

The `key` is visible in the props list to the right.

### Detailed Proposal

As mentioned below in https://github.com/facebook/react/issues/18702#issuecomment-617924196

Add a light divider and new section in the props panel to the right.

Potentially also add a question mark that shows an explanation about the fact that things in this section are not really props.

Ref (Original implementation): https://github.com/facebook/react-devtools/pull/328
};
export type Handler = (data: any) => void;
export type DevToolsHook = {
  listeners: {[key: string]: Array<Handler>, ...},
  rendererInterfaces: Map<RendererID, RendererInterface>,
  renderers: Map<RendererID, ReactRenderer>,
  emit: (event: string, data: any) => void,
  getFiberRoots: (rendererID: RendererID) => Set<Object>,
  inject: (renderer: ReactRenderer) => number | null,
  on: (event: string, handler: Handler) => void,
  off: (event: string, handler: Handler) => void,
  reactDevtoolsAgent?: ?Object,
  sub: (event: string, handler: Handler) => () => void,
  
  resolveRNStyle?: ResolveNativeStyle,
  nativeStyleEditorValidAttributes?: $ReadOnlyArray<string>,
  
  checkDCE: (fn: Function) => void,
  onCommitFiberUnmount: (rendererID: RendererID, fiber: Object) => void,
  onCommitFiberRoot: (
    rendererID: RendererID,
    fiber: Object,
    
    commitPriority?: number,
    
    didError?: boolean,
  ) => void,
  ...
};