title: How to change the color of the PreferenceCategory divider in PreferenceScreen
body: <p>I have an <a href="https://github.com/kolavar/android-support-v4-preferencefragment" rel="noreferrer">android.support.v4.preference.PreferenceFragment</a> which uses the following PreferenceScreen:</p>
  
  <pre><code>&lt;PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"&gt;
  &lt;PreferenceCategory
      android:title="Cat1"
      android:key="pref_cat1"&gt;
      &lt;ListPreference
          android:key="pref_list1"
          android:title="@string/pref_list1"
          android:dialogTitle="@string/pref_list1"
          android:entries="@array/pref_list1_entries"
          android:entryValues="@array/pref_list1_entries"
          android:defaultValue="@string/pref_list1_default"/&gt;
      &lt;EditTextPreference
          android:key="pref_text2"
          android:title="@string/pref_text2"
          /&gt;
  &lt;/PreferenceCategory&gt;
  &lt;PreferenceCategory
      android:title="Cat2"
      android:key="pref_cat2"&gt;
      &lt;EditTextPreference
          android:key="pref_text3"
          android:title="@string/pref_text3"
          /&gt;
  &lt;/PreferenceCategory&gt;
  </code></pre>
  
  <p></p>
  
  <p>When displaying the PreferenceFragment, some dividers are shown between the preferences, but also under the name of each PreferenceCategory.
  Though I can easily modify the color of the dividers between the preferences by accessing the PreferenceFragment's ListView, this has no effect on the PreferenceCategory dividers.</p>
  
  <p>How to change also the color of such dividers?</p>