How can I set width of element in percent?
<p>My question is very easy. I have layout:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:background="@drawable/mobile_background"
    android:layout_width="fill_parent"
    android:gravity="center"
    android:layout_height="fill_parent"
    &gt;
    &lt;Button 
        android:text="GET MESSAGES" 
        android:
        android:id="@+id/buttonMessages" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" /&gt;
    &lt;Button 
        android:text="REGISTRATION" 
        android:id="@+id/buttonRegistration" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" /&gt;
    &lt;Button 
        android:text="SETTINGS" 
        android:id="@+id/buttonSettings" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" /&gt;
&lt;/LinearLayout&gt;
</code></pre>

<p>But I need to set non-fixed size for button - I need to set size 30% of screen width. How can I do it? </p>
