title: How to make a view to cover your screen despite different screens
body: <p>I have one layout in which there is one relative layout inside main layout.This layout is displayed in center of the main layout.In some device it is covering most part(having some widgets above and below it).I tested it with different emulators.In some mulator it is not covering that much are.I want it should cover same portion in every screen(i.e. in every emulator).Can i use Layout:weight ?  any better idea ?</p>
  
  <pre><code>&lt;LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android" 
    style="@style/ViewScreenTheme"
    android:orientation="vertical"
    android:background="@drawable/background"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"&gt;
  
  &lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"&gt;
    &lt;RelativeLayout android:id="@+id/header" 
      android:orientation="horizontal"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:gravity="center_horizontal"
      android:paddingTop="10dp"
      android:paddingBottom="10dp"&gt;
  
      &lt;Button android:id="@+id/help_button" 
        android:layout_alignParentRight="true"
        style="@style/ButtonText"
        android:layout_margin="1dp"
        android:layout_height="wrap_content" 
        android:layout_width="wrap_content"
        android:background="@drawable/help_button"
        android:paddingLeft="10px"
        android:paddingRight="10px"
        android:layout_marginRight="10px"/&gt;
    &lt;/RelativeLayout&gt;
    &lt;RelativeLayout android:id="@+id/root" 
      android:orientation="horizontal"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:gravity="center_horizontal"
      android:layout_below="@+id/header"
      android:layout_marginTop="2dp"
      android:layout_marginBottom="0dp"
      android:paddingTop="10dp"
      android:paddingBottom="10dp"&gt;
      &lt;RelativeLayout
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="384dp"
        android:background="#0fff"
        android:id="@+id/canvas_layout"&gt;
      &lt;/RelativeLayout&gt;
    &lt;/RelativeLayout&gt;
  &lt;/RelativeLayout&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>I want canvas_layout which is last relative layout to cover some part in every screen.</p>