Use this style , declare in manifest
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="Theme.Transparent" parent="android:Theme">
<item name="android:windowIsTranslucent">true</item>
<item name="android:windowNoTitle">true</item>
<item name="android:windowContentOverlay">@null</item>
<item name="android:backgroundDimEnabled">false</item>
<item name="android:windowIsFloating">true</item>
<item name="android:windowBackground">@android:color/transparent</item>
</style>
</resources>
or use
android:theme="@android:style/Theme.Translucent"
Download sample code here
