<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/callemall/material-ui/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<p dir="auto">This is just a discussion over documentation of v1.</p>
<p dir="auto">In this section : <a href="https://material-ui.com/customization/overrides/#overriding-with-classes" rel="nofollow">https://material-ui.com/customization/overrides/#overriding-with-classes</a> it seems in both the text description, and the example, that the classes override <strong>replace</strong> the default one.This is not very intuitive as classes are string, not objects that can merge, which is why I thought it worked that way in the first place.</p>
<p dir="auto">An explicitly description of how it works could make things clearer, . <em>ie.</em> the styles objects pointed by both the overriding class name and the default one, are merged together.</p>
<p dir="auto">What do you think?</p>
<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">Passing loop element to MenuItem onClick, the elements is always the last element in the array.</p>
<h2 dir="auto">Current Behavior</h2>
<p dir="auto">Passing loop element to MenuItem onClick should pass the current element being iterated over.</p>
<h2 dir="auto">Steps to Reproduce (for bugs)</h2>

<ol dir="auto">
<li>go to <a href="https://codesandbox.io/s/y3z5kq8mvz" rel="nofollow">https://codesandbox.io/s/y3z5kq8mvz</a></li>
<li>Click any item in 'open one' and it will console.log 'closing two'. It should console.log 'closing one'.</li>
</ol>
<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>beta23</td>
</tr>
<tr>
<td>React</td>
<td>16.2.0</td>
</tr>
<tr>
<td>browser</td>
<td>chrome 62</td>
</tr>
<tr>
<td>etc</td>
<td>macos</td>
</tr>
</tbody>
</table>