All this does is allow it to be added to the Multi-view slide out bar. Some apps it works with and some it does not. De-compile the apk and insert this into the xml file.
This needs to go into the correct places in the xml file. <category android:name="android.intent.category.MULTIWINDOW_LAUNCHER" />
<uses-library required="false" name="com.sec.android.app.multiwindow" />
<meta-data android:name="com.sec.android.support.multiwindow" android:value="true" />
<meta-data android:name="com.sec.android.multiwindow.DEFAULT_SIZE_W" android:value="632.0dip" />
<meta-data android:name="com.sec.android.multiwindow.DEFAULT_SIZE_H" android:value="598.0dip" />
<meta-data android:name="com.sec.android.multiwindow.MINIMUM_SIZE_W" android:value="632.0dip" />
<meta-data android:name="com.sec.android.multiwindow.MINIMUM_SIZE_H" android:value="598.0dip" />
It is pretty easy to do. I am hoping that Subsonic will update there app soon.
This processes is done using apk multi-tool. You can read more about it
http://apkmultitool.com/.