You will need to get the image like this:
from java.awt import Toolkit, Point
from com.inductiveautomation.ignition.client.images import ImageLoader
tk = Toolkit.getDefaultToolkit()
img = ImageLoader.getInstance().loadImage("Cursors/green.png")
c = tk.createCustomCursor(img, Point(event.source.parent.getX(), event.source.parent.getY()), "img")
event.source.parent.setCursor(c)