title: Set gradient for Android ActionBar
body: <p>I use an ActionBarSherlock library in my app. I also needed to customize the ActionBar, so I added a custom theme with a <code>background</code> parameter set, like this:</p>
  
  <pre><code>&lt;style name="Widget.Styled.ActionBar" parent="Widget.Sherlock.Light.ActionBar.Solid.Inverse"&gt;
  
  &lt;item name="background"&gt;@drawable/action_bar_bg&lt;/item&gt;
  
  &lt;item name="android:background"&gt;@drawable/action_bar_bg&lt;/item&gt;
  
  &lt;/style&gt;
  </code></pre>
  
  <p><code>action_bar_bg</code> drawable is simply a bitmap of tiled squares:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  
  &lt;bitmap xmlns:android="http://schemas.android.com/apk/res/android"
      android:dither="true"
      android:src="@drawable/bg_img_actionbar"
      android:tileMode="repeat" /&gt;
  </code></pre>
  
  <p>What I want to do next is to set a linear gradient for a whole ActionBar, so it will cover this background. And I have no idea if it's possible and how to do that.
  Any help would be appreciated.</p>