import xbmc, os

guisettingsFile=xbmc.translatePath("special://profile/guisettings.xml")

fh=open(guisettingsFile, 'r')
content= fh.read()
fh.close()

settingValue="visualization.milkdrop"

if content.find("<visualisation></visualisation>")>=0:
  xbmc.executehttpapi("SetGUISetting(3;musicplayer.visualisation;"+settingValue+")")
elif content.find("<visualisation>"+settingValue+"</visualisation>")>=0:
  xbmc.executehttpapi("SetGUISetting(3;musicplayer.visualisation;)")
xbmc.executebuiltin("ReloadSkin()")