## 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
const roots =
      renderer.Mount._instancesByReactRootID ||
      renderer.Mount._instancesByContainerID;
    for (const key in roots) {
      const internalInstance = roots[key];
      const id = getID(internalInstance);
      crawlAndRecordInitialMounts(id, 0, id);
      flushPendingEvents(id);
    }
  }
  const pendingOperations: Array<number> = [];
  const pendingStringTable: Map<string, number> = new Map();
  let pendingUnmountedIDs: Array<number> = [];
  let pendingStringTableLength: number = 0;
  let pendingUnmountedRootID: number | null = null;
  function flushPendingEvents(rootID: number) {
    if (
      pendingOperations.length === 0 &&
      pendingUnmountedIDs.length === 0 &&
      pendingUnmountedRootID === null
    ) {
      return;
    }
    const numUnmountIDs =
      pendingUnmountedIDs.length + (pendingUnmountedRootID === null ? 0 : 1);
    const operations = new Array(