<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have searched the <a href="https://github.com/mui-org/material-ui/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h2 dir="auto">Expected Behavior</h2>

<p dir="auto">Orientation in  StepButton's props should be optional as document described.</p>
<h2 dir="auto">Current Behavior</h2>

<p dir="auto">Orientation is a required prop, cause type missmatch.</p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>

<div class="highlight highlight-source-ts notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="&lt;StepButton /&gt;"><pre class="notranslate"><span class="pl-c1">&lt;</span><span class="pl-smi">StepButton</span> <span class="pl-c1">/</span><span class="pl-c1">&gt;</span></pre></div>
<p dir="auto">ERROR in /xxx/xx.tsx<br>
[tsl] ERROR in /xxx/xx.tsx(240,29)<br>
TS2322: Type '{ children: string[]; }' is not assignable to type 'IntrinsicAttributes &amp; StepButtonProps &amp; { children?: ReactNode; }'.<br>
Type '{ children: string[]; }' is not assignable to type 'StepButtonProps'.<br>
Property 'orientation' is missing in type '{ children: string[]; }'.</p>
<h2 dir="auto">Context</h2>

<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>Material-UI</td>
<td>1.0.0-beta.27</td>
</tr>
<tr>
<td>TypeScript</td>
<td>2.6.2</td>
</tr>
</tbody>
</table>
<h3 dir="auto">Problem description</h3>
<p dir="auto">React release 15.2.0 will cause some of the components generating<br>
Unknown prop <code class="notranslate">tooltipPosition</code> on  tag. Remove this prop from the element. For details, see <a href="https://fb.me/react-unknown-prop" rel="nofollow">https://fb.me/react-unknown-prop</a></p><p dir="auto"></p>
<p dir="auto">Referring <a href="https://gist.github.com/jimfb/d99e0678e9da715ccf6454961ef04d1b">https://gist.github.com/jimfb/d99e0678e9da715ccf6454961ef04d1b</a></p>
<h3 dir="auto">Versions</h3>
<ul dir="auto">
<li>Material-UI: 0.15.1</li>
<li>React: 15.2.0</li>
<li>Browser: Chrome</li>
</ul>

<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/6867081/16677133/94ab0c9e-4515-11e6-925d-7e28d62a27c8.png"><img src="https://cloud.githubusercontent.com/assets/6867081/16677133/94ab0c9e-4515-11e6-925d-7e28d62a27c8.png" alt="screen shot 2016-07-08 at 2 09 00 pm" style="max-width: 100%;"></a></p><p></p>