<p dir="auto">I hit CTRL+Z one too many times and it displayed the code from the previous challenge. I did a hard refresh and still have the code you see below. A screenshot is attached as well.<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/25393587/22738951/a6abe24a-edd7-11e6-898c-2cdc25815a78.png"><img src="https://cloud.githubusercontent.com/assets/25393587/22738951/a6abe24a-edd7-11e6-898c-2cdc25815a78.png" alt="screen shot 2017-02-08 at 8 19 34 am" style="max-width: 100%;"></a></p>
<p dir="auto"><a href="http://beta.freecodecamp.com/en/challenges/applied-visual-design/adjust-the-hue-of-a-color" rel="nofollow">adjust-the-hue-of-a-color</a> has an issue.<br>
User Agent is: <code class="notranslate">Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.95 Safari/537.36</code>.<br>
Please describe how to reproduce this issue, and include links to screenshots if possible.</p>
<div class="highlight highlight-text-html-basic notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="

&lt;style&gt;
  body {
    background-color: white;
  }
  header {
    background-color: #09A7A1;
    color: white;
    padding: 0.25em;
  }
  h2 {
    color: #09A7A1;
  }  
  button {
    background-color: #FF790E;
  }
  footer {
    background-color: #09A7A1;
    color: white;
    padding: 0.5em;
  }
&lt;/style&gt;
&lt;header&gt;
  &lt;h1&gt;Cooking with FCC!&lt;/h1&gt;
&lt;/header&gt;
&lt;main&gt;
  &lt;article&gt;
    &lt;h2&gt;Machine Learning in the Kitchen&lt;/h2&gt;
    &lt;p&gt;Join this two day workshop that walks through how to implement cutting-edge snack-getting algorithms with a command line interface. Coding usually involves writing exact instructions, but sometimes you need your computer to execute flexible commands, like &lt;code&gt;fetch Pringles&lt;/code&gt;.&lt;/p&gt;
    &lt;button&gt;Sign Up&lt;/button&gt;
  &lt;/article&gt;
  &lt;article&gt;
    &lt;h2&gt;Bisection Vegetable Chopping&lt;/h2&gt;
    &lt;p&gt;This week-long retreat will level-up your coding ninja skills to actual ninja skills. No longer is the humble bisection search limited to sorted arrays or coding interview questions, applying its concepts in the kitchen will have you chopping carrots in O(log n) time before you know it.&lt;/p&gt;
    &lt;button&gt;Sign Up&lt;/button&gt;
  &lt;/article&gt;
&lt;/main&gt;
&lt;br&gt;
&lt;footer&gt;&amp;copy;2016 FCC Kitchen&lt;/footer&gt;
"><pre class="notranslate"><span class="pl-kos">&lt;</span><span class="pl-ent">style</span><span class="pl-kos">&gt;</span>
  <span class="pl-ent">body</span> {
    <span class="pl-c1">background-color</span><span class="pl-kos">:</span> white;
  }
  <span class="pl-ent">header</span> {
    <span class="pl-c1">background-color</span><span class="pl-kos">:</span> <span class="pl-pds"><span class="pl-kos">#</span>09A7A1</span>;
    <span class="pl-c1">color</span><span class="pl-kos">:</span> white;
    <span class="pl-c1">padding</span><span class="pl-kos">:</span> <span class="pl-c1">0.25<span class="pl-smi">em</span></span>;
  }
  <span class="pl-ent">h2</span> {
    <span class="pl-c1">color</span><span class="pl-kos">:</span> <span class="pl-pds"><span class="pl-kos">#</span>09A7A1</span>;
  }  
  <span class="pl-ent">button</span> {
    <span class="pl-c1">background-color</span><span class="pl-kos">:</span> <span class="pl-pds"><span class="pl-kos">#</span>FF790E</span>;
  }
  <span class="pl-ent">footer</span> {
    <span class="pl-c1">background-color</span><span class="pl-kos">:</span> <span class="pl-pds"><span class="pl-kos">#</span>09A7A1</span>;
    <span class="pl-c1">color</span><span class="pl-kos">:</span> white;
    <span class="pl-c1">padding</span><span class="pl-kos">:</span> <span class="pl-c1">0.5<span class="pl-smi">em</span></span>;
  }
<span class="pl-kos">&lt;/</span><span class="pl-ent">style</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;</span><span class="pl-ent">header</span><span class="pl-kos">&gt;</span>
  <span class="pl-kos">&lt;</span><span class="pl-ent">h1</span><span class="pl-kos">&gt;</span>Cooking with FCC!<span class="pl-kos">&lt;/</span><span class="pl-ent">h1</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;/</span><span class="pl-ent">header</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;</span><span class="pl-ent">main</span><span class="pl-kos">&gt;</span>
  <span class="pl-kos">&lt;</span><span class="pl-ent">article</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">h2</span><span class="pl-kos">&gt;</span>Machine Learning in the Kitchen<span class="pl-kos">&lt;/</span><span class="pl-ent">h2</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">p</span><span class="pl-kos">&gt;</span>Join this two day workshop that walks through how to implement cutting-edge snack-getting algorithms with a command line interface. Coding usually involves writing exact instructions, but sometimes you need your computer to execute flexible commands, like <span class="pl-kos">&lt;</span><span class="pl-ent">code</span><span class="pl-kos">&gt;</span>fetch Pringles<span class="pl-kos">&lt;/</span><span class="pl-ent">code</span><span class="pl-kos">&gt;</span>.<span class="pl-kos">&lt;/</span><span class="pl-ent">p</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">button</span><span class="pl-kos">&gt;</span>Sign Up<span class="pl-kos">&lt;/</span><span class="pl-ent">button</span><span class="pl-kos">&gt;</span>
  <span class="pl-kos">&lt;/</span><span class="pl-ent">article</span><span class="pl-kos">&gt;</span>
  <span class="pl-kos">&lt;</span><span class="pl-ent">article</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">h2</span><span class="pl-kos">&gt;</span>Bisection Vegetable Chopping<span class="pl-kos">&lt;/</span><span class="pl-ent">h2</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">p</span><span class="pl-kos">&gt;</span>This week-long retreat will level-up your coding ninja skills to actual ninja skills. No longer is the humble bisection search limited to sorted arrays or coding interview questions, applying its concepts in the kitchen will have you chopping carrots in O(log n) time before you know it.<span class="pl-kos">&lt;/</span><span class="pl-ent">p</span><span class="pl-kos">&gt;</span>
    <span class="pl-kos">&lt;</span><span class="pl-ent">button</span><span class="pl-kos">&gt;</span>Sign Up<span class="pl-kos">&lt;/</span><span class="pl-ent">button</span><span class="pl-kos">&gt;</span>
  <span class="pl-kos">&lt;/</span><span class="pl-ent">article</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;/</span><span class="pl-ent">main</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;</span><span class="pl-ent">br</span><span class="pl-kos">&gt;</span>
<span class="pl-kos">&lt;</span><span class="pl-ent">footer</span><span class="pl-kos">&gt;</span>&amp;copy;2016 FCC Kitchen<span class="pl-kos">&lt;/</span><span class="pl-ent">footer</span><span class="pl-kos">&gt;</span></pre></div>
<p dir="auto">Steps to reproduce:</p>
<ol dir="auto">
<li>go to one of a challenge</li>
<li>click "Map"</li>
<li>click another challenge</li>
<li>repeat step 2 and 4 as many as you want</li>
<li>CTRL-Z (undo) in the editor will restore the editor to previous challenge</li>
</ol>
<p dir="auto">Expectation:</p>
<ul dir="auto">
<li>when a challenge is opened, the CTRL-Z (undo) history expected to be cleared</li>
</ul>
<p dir="auto">Related with <a href="https://github.com/FreeCodeCamp/FreeCodeCamp/issues/806#issuecomment-249366799" data-hovercard-type="issue" data-hovercard-url="/freeCodeCamp/freeCodeCamp/issues/806/hovercard">this</a></p>
<p dir="auto">Codemirror has ability to clear undo history but in beta site we are using React (<code class="notranslate">react-codemirror</code>)</p>
<p dir="auto">So the way to handle it might be different</p>