title: Changes from one branch are also applied (kept) in other branches? (PhpStorm & Git)
body: <p>I'm using PhpStorm 2018.2.4 (Ubuntu 18).</p>
  
  <p>Let's say that I've pulled the <code>develop</code> branch from GitHub repo (project) and there are 2 files in the project:</p>
  
  <ul>
  <li>file_1.php</li>
  <li>file_2.php</li>
  </ul>
  
  <p>Then I create a new branch in PhpStorm named <code>feature/something</code> and checkout ( <em>in the Branches popup, I choose <strong>New Branch</strong>, select <strong>Checkout branch</strong> option and enter name</em> ... ).</p>
  
  <p>Now I'm on <code>feature/something</code>. </p>
  
  <p>I do some changes in <em>file_1.php</em> and in the PhpStorm's file browser it becomes <strong>blue</strong> (as expected).</p>
  
  <p>BUT, when I go (checkout) back to <code>develop</code> branch - the changes I've made when I was on <code>feature/something</code> are kept (are also applied) on <code>develop</code> branch: </p>
  
  <ul>
  <li><em>file_1.php</em> is still 'blue'</li>
  <li>changes in <em>file_1.php</em> are there...</li>
  </ul>
  
  <p>Is this supposed to work like that OR when I move back (checkout) to <code>develop</code> branch - the changes from <code>feature/something</code> should not be applied (kept) in <code>develop</code>?</p>
  
  <ul>
  <li><p>If this is normal - then how can I move back to the "original" (clean) <code>develop</code> (without the chages from the other local branch)? If I do <code>revert</code> while on <code>develop</code> - then when I move (checkout) back to the <code>feature/something</code> - those changes were reverted there too.</p></li>
  <li><p>If this is not supposed to work like this, how can I fix it?</p></li>
  </ul>