title: android: Why attribute clipChildren doesn't work in RelativeLayout but works in LinearLayout
body: <p>I'm very confused about why attribute clipChildren doesn't work in RelativeLayout but works in LinearLayout. 
  I put a LinearLayout and a RelativeLayout in a parent RelativeLayout. And set clipChildren to 'false' of these three layouts. But it shows difference.
  codes as follows:</p>
  
  <pre><code>&lt;RelativeLayout 
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:clipChildren="false"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:orientation="vertical"&gt;
  
      &lt;LinearLayout
          android:clipChildren="false"
          android:clipToPadding="false"
          android:background="#ff0000"
          android:layout_marginTop="200dp"
          android:layout_width="100dp"
          android:layout_height="200dp"&gt;
  
          &lt;Button
              android:background="@color/colorPrimaryDark"
              android:layout_width="300dp"
              android:layout_height="100dp" /&gt;
  
      &lt;/LinearLayout&gt;
  
      &lt;RelativeLayout
          android:clipChildren="false"
          android:clipToPadding="false"
          android:background="#ff0000"
          android:layout_width="100dp"
          android:layout_height="200dp"&gt;
  
          &lt;Button
              android:background="@color/colorPrimaryDark"
              android:layout_width="300dp"
              android:layout_height="100dp" /&gt;
  
      &lt;/RelativeLayout&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>and result as follows:
  <a href="https://i.stack.imgur.com/YNNPA.png" rel="nofollow noreferrer">image of result</a></p>