## 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
pendingUnmountedIDs.push(id);
    idToInternalInstanceMap.delete(id);
  }
  function crawlAndRecordInitialMounts(
    id: number,
    parentID: number,
    rootID: number,
  ) {
    if (__DEBUG__) {
      console.group('crawlAndRecordInitialMounts() id:', id);
    }
    const internalInstance = idToInternalInstanceMap.get(id);
    if (internalInstance != null) {
      internalInstanceToRootIDMap.set(internalInstance, rootID);
      recordMount(internalInstance, id, parentID);
      getChildren(internalInstance).forEach(child =>
        crawlAndRecordInitialMounts(getID(child), id, rootID),
      );
    }
    if (__DEBUG__) {
      console.groupEnd();
    }
  }
  function flushInitialOperations() {