title: why isn't ScaleDrawable displayed?
body: <p>I'm defining a <code>ScaleDrawable</code> in XML according to the Android developers site example:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
      &lt;scale xmlns:android="http://schemas.android.com/apk/res/android"
      android:drawable="@drawable/sign_ui_text_line"
      android:scaleGravity="center_vertical|center_horizontal"
      android:scaleHeight="80%"
      android:scaleWidth="80%" /&gt;
  </code></pre>
  
  <p>I define this as the background of an <code>EditText</code></p>
  
  <p>for some reason the drawable isn't displayed (but the <code>EditText</code> view changes it's size according to the definitions).</p>
  
  <p>why doesn't it display ?</p>
  
  <p>how can I scale a drawable to be used as a background ?</p>