title: Styled Spinner shows dropdown list as dialog
body: <p>after styling my spinner, the dropdown list popup like dialogs, 
  i tried to set </p>
  
  <pre><code>    &lt;item name="android:spinnerMode"&gt;dropdown&lt;/item&gt;
  </code></pre>
  
  <p>but the result was like this</p>
  
  <p><img src="https://i.stack.imgur.com/UFPSW.png" alt="enter image description here"></p>
  
  <p>i don't like this shadow .</p>
  
  <p>and when i remove the previous line ; i get this result </p>
  
  <p><img src="https://i.stack.imgur.com/IF1eT.png" alt="enter image description here"></p>
  
  <p>here is my spinner part of style.xml</p>
  
  <pre><code> &lt;style name="MyTheme.SpinnerAppTheme" parent="android:Widget.Spinner"&gt;
          &lt;item name="android:background"&gt;@drawable/apptheme_spinner_background_holo_dark&lt;/item&gt;
          &lt;item name="android:spinnerMode"&gt;dropdown&lt;/item&gt;&lt;!--i really don't like the result of this line--&gt;
          &lt;item name="android:dropDownListViewStyle"&gt;@android:style/Widget.Spinner.DropDown&lt;/item&gt;
      &lt;/style&gt;
  </code></pre>
  
  <p>the question is <strong>How to get back the default dropdown style</strong></p>