title: How to extend prop types of Material UI components using Flow when passing through props?
body: <p>I'd like to add Flow Types to an existing React project which uses Material UI.
  I have a number of components which render a Material UI component and pass through any props received. For example:</p>
  
  <pre><code>import React from "react";
  import IconButton from "@material-ui/core/IconButton";
  import backIcon from "assets/icons/Back.svg";
  
  const BackButton = ({ height, ...props }) =&gt; (
    &lt;IconButton {...props}&gt;
      &lt;img
        src={backIcon}
        alt="back"
        style={{
          height,
          width: height
        }}
      /&gt;
    &lt;/IconButton&gt;
  );
  
  BackButton.defaultProps = {
    height: "1.5rem"
  };
  
  export default BackButton;
  </code></pre>
  
  <p>If I were to define prop types for this, I figure it would look something like</p>
  
  <pre><code>type BackButtonProps = IconButtonProps &amp; {
    height: string
  }
  
  const BackButton = ({height, ...props}): BackButtonProps =&gt; (
    ...
  )
  </code></pre>
  
  <p>My issue is that I'm not sure where to get <code>IconButtonProps</code> from. I've run <code>flow-typed install</code> and have a <code>flow-typed/npm/@material-ui</code> folder, but I can't figure out how to import <code>IconButtonProps</code>. I've tried the following:</p>
  
  <pre><code>import type { IconButtonProps } from "@material-ui/core/IconButton"
  </code></pre>
  
  <p>But the import is unresolved.
  Where can I import the prop types of Material UI components from, in order to be able to extend them?</p>