title: Why Android Studio is removing and/or changing layout_margin* constraints?
body: <p>I'm using <code>android.support.constraint.ConstraintLayout</code> to layout a simple card's content views.</p>
  <p>I'm getting random changes in my XML, every time, when:</p>
  <ul>
  <li>I switch to Android Studio's layout editor's <code>Design</code> tab</li>
  <li>Or when I have a <code>Preview</code> pane turned on (in this case changes happens even more often during my changes).</li>
  </ul>
  <p>Those random changes include:</p>
  <ul>
  <li>Removal of my manually defined layout margins (eg. <code>layout_marginEnd</code>)</li>
  <li>Changing values of my manually entered margin value</li>
  <li>Adding <code>tools:layout_editor_absoluteX</code> values</li>
  </ul>
  <p>Questions:</p>
  <ul>
  <li>Anyone else experience this Android Studio's feature?</li>
  <li>How to switch this &quot;feature&quot; off, so my layouts would not be destroyed?</li>
  <li>Where to report this bug to Google or JetBrains?</li>
  </ul>
  <p>Please take a look to this file diff, which was made automatically when switched to Design tab:
  <a href="https://i.stack.imgur.com/HRDZm.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/HRDZm.jpg" alt="Automatically made changes' diff in layout XML file" /></a></p>
  <p>PS.: My Android Studio version is <code>2.2.3</code>; I'm running it on macOS Sierra.</p>
  <h2>Update #1</h2>
  <p>As suggested, after making <code>layout_height=&quot;match_parent&quot;</code>, I get modifications less often, but still my XML gets messed-up, when I edit layout in Layout Design'er:
  <a href="https://i.stack.imgur.com/MohHC.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/MohHC.jpg" alt="Automatic changes #2" /></a>
  This time I wanted to set <code>layout_marginTop</code> through Design UI (selected line is what I wanted to add), but I also got those other unwanted changes:</p>
  <ul>
  <li><code>layout_marginStart</code> removed;</li>
  <li><code>app:layout_constraintBottom_toBottomOf</code> referenced IDs got a prefix of &quot;+&quot; sign, which means, those IDs are newly declared, so when I'll use <code>Goto declaration</code> functionality, I'll have to choose it from the list - not a desired behaviour.</li>
  <li><code>tools:layout_editor_absoluteX</code> gets added. I could ignore it, but still - not what I'd want to happen.</li>
  </ul>