title: how to call the ok button in the EditTextPreference
body: <p>I have an <code>EditTextPreference</code> in the <code>PreferenceActivity</code>. When user click the  <code>EditTextPreference</code> will show  a dialog. In the dialog, user can input a value, and the dialog has "OK" and "Cancel" buttons. I want to call the click event of <strong>ok</strong> button to check the value, but I do not know how to call the click even.</p>
  
  <p>I know I can use <code>EditTextPreference.setOnPreferenceChangeListener()</code>, but I want to know if I can use OK button click event.</p>