What makes a button change color on mouseclick?
<p>Why is this button changing color to orange when clicked:  </p>

<pre><code>&lt;Button android:background="@android:drawable/btn_plus" ...&gt;
</code></pre>

<p>but this one is not?   </p>

<pre><code>&lt;Button android:background="@drawable/ic_btn_round_plus" ...&gt;   
</code></pre>

<p>Edit:<br>
Found another type of button (text and image) that changes color to orange when clicked<br>
without having to create a selector:  </p>

<pre><code>&lt;Button android:text="List" android:drawableTop="@drawable/list" ...&gt;       
</code></pre>
