If you have a version before advanced stylesheets (8.1.22), I found this (really hacky) workaround:
This would go on a binding on the style
def transform(self, value, quality, timestamp):
style = {}
style['fontSize'] = 60
style['color']='magenta'
style['-webkit-text-stroke']='2px green'
return style
I don't really recommend it but it does seem to work: