Android Tips: Using a live wallpaper as your app’s background
This one took a while to find so it’s worthy of a tip :)
To use the current live wallpaper as your app’s background, simply set the theme for your activity to @android:style/Theme.Wallpaper in your AndroidManifest.xml:
... <activity .... android:theme="@android:style/Theme.Wallpaper"> ... </activity>