Karabiner (KeyRemap4MacBook) remap "Play" OSX Key to launch Spotify

private.xml

<?xml version="1.0"?>
<root>
	<!-- Spotify Path -->
	<vkopenurldef>
		<name>KeyCode::VK_OPEN_URL_APP_Spotify</name>
		<url type="file">/Applications/Spotify.app</url>
	</vkopenurldef>

	<!-- Set Spotify definition -->
	<appdef>
		<appname>SPOTIFY</appname>
		<equal>com.spotify.client</equal>
	</appdef>

	<!-- Use 'Music Play' key to launch Spotify if not ever in the application or ITunes -->
	<!-- Else, act as normal play/pause button in Spotify, Itunes -->
	<item>
		<name>Change Play key to launch Spotify</name>
		<identifier>private.play_launch_spotify</identifier>
		<not>SPOTIFY, ITUNES</not>
		<autogen>
			__KeyToKey__,
			ConsumerKeyCode::MUSIC_PLAY,
			KeyCode::VK_OPEN_URL_APP_Spotify,
		</autogen>
	</item>
</root>

Is there a way to make this only open Spotify if it's not open, and otherwise just play/pause music in Spotify?