<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>
<p dir="auto">Got the following error when using the ExpansionPanel:</p>
<blockquote>
<p dir="auto">Types of property 'onChange' are incompatible.<br>
Type '(_: any, expanded: any) =&gt; void' is not assignable to type '(event: SyntheticEvent&lt;{}&gt;) =&gt; void'.</p>
</blockquote>

<h2 dir="auto">Steps to Reproduce (for bugs)</h2>
<p dir="auto">Any <code class="notranslate">ExpansionPanel</code> using the <code class="notranslate">onChange</code> with the <code class="notranslate">expanded</code> parameter:</p>
<div class="highlight highlight-source-js notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="&lt;ExpansionPanel
  expanded={props.expanded}
  onChange={(_, expanded) =&gt; props.onChange(expanded)}
/&gt;"><pre class="notranslate"><span class="pl-c1">&lt;</span><span class="pl-ent">ExpansionPanel</span>
  <span class="pl-c1">expanded</span><span class="pl-c1">=</span><span class="pl-kos">{</span><span class="pl-s1">props</span><span class="pl-kos">.</span><span class="pl-c1">expanded</span><span class="pl-kos">}</span>
  <span class="pl-c1">onChange</span><span class="pl-c1">=</span><span class="pl-kos">{</span><span class="pl-kos">(</span><span class="pl-s1">_</span><span class="pl-kos">,</span> <span class="pl-s1">expanded</span><span class="pl-kos">)</span> <span class="pl-c1">=&gt;</span> <span class="pl-s1">props</span><span class="pl-kos">.</span><span class="pl-en">onChange</span><span class="pl-kos">(</span><span class="pl-s1">expanded</span><span class="pl-kos">)</span><span class="pl-kos">}</span>
<span class="pl-c1">/</span><span class="pl-c1">&gt;</span></pre></div>
<p dir="auto">The last example on the demo page should trigger the error<br>
<a href="https://material-ui.com/demos/expansion-panels/#controlled-accordion" rel="nofollow">https://material-ui.com/demos/expansion-panels/#controlled-accordion</a></p>
<p dir="auto">Also I looked in the typescript tests and didn't find one that uses the onChange with the expanded.</p>
<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>Material-UI</td>
<td>1.0.0-beta.25</td>
</tr>
<tr>
<td>React</td>
<td>16.2.0</td>
</tr>
<tr>
<td>browser</td>
<td>electron 1.8.1</td>
</tr>
</tbody>
</table>
<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>
<p dir="auto">Here is my code</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="&lt;Drawer
       leftBarOpen={this.leftBarOpen}
       containerStyle={{height:'calc(100% - 120px)'}}
       docked={docked}
       zDepth={zDepth}
       open={this.state.leftBarOpen}
       width={drawerWidth}
       openSecondary={false}
      disableSwipeToOpen={true}
      swipeAreaWidth={50}
      onRequestChange={(open) =&gt; this.setState({leftBarOpen: false})}&gt;                 
&lt;/Drawer&gt;"><pre class="notranslate"><code class="notranslate">&lt;Drawer
       leftBarOpen={this.leftBarOpen}
       containerStyle={{height:'calc(100% - 120px)'}}
       docked={docked}
       zDepth={zDepth}
       open={this.state.leftBarOpen}
       width={drawerWidth}
       openSecondary={false}
      disableSwipeToOpen={true}
      swipeAreaWidth={50}
      onRequestChange={(open) =&gt; this.setState({leftBarOpen: false})}&gt;                 
&lt;/Drawer&gt;
</code></pre></div>
<h2 dir="auto">Expected Behavior</h2>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/19373581/35316582-645b03ae-010d-11e8-841c-e5344a99741e.png"><img src="https://user-images.githubusercontent.com/19373581/35316582-645b03ae-010d-11e8-841c-e5344a99741e.png" alt="image" style="max-width: 100%;"></a></p>
<h2 dir="auto">Current Behavior</h2>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/19373581/35316741-356b1632-010e-11e8-9f2e-9088aa9603f0.png"><img src="https://user-images.githubusercontent.com/19373581/35316741-356b1632-010e-11e8-9f2e-9088aa9603f0.png" alt="image" style="max-width: 100%;"></a></p>
<h4 dir="auto">It works well on React v15.6.2 &amp;&amp; Material-UI v0.20.0</h4>
<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>0.20.0</td>
</tr>
<tr>
<td>React</td>
<td>16.2.0</td>
</tr>
<tr>
<td>browser</td>
<td>chrome</td>
</tr>
<tr>
<td>etc</td>
<td>mac</td>
</tr>
</tbody>
</table>