title: No grammar constraints (DTD or XML schema) detected for the document (Android)
body: <p>I have the same problem as many here, but i DO HAVE xmlns:android and the xml=... tags.
  Still I have the same error. I don't wan't just click the ignore instead of warning in the settings so hence the question here posted.</p>
  
  <p>The source is:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;GridLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="match_parent" &gt;
  
  
  &lt;/GridLayout&gt;
  </code></pre>
  
  <p>The error:</p>
  
  <blockquote>
    <p>"No grammar constraints (DTD or XML schema) detected for the
    document. grid_layout_test2.xml   /SomeProject/res/layout line 1  XML
    Problem"</p>
  </blockquote>