.load file sends parent URL to a controller in long form, including alll parts of the URL:
controller then does a redirect to parent
how to get the abreviated form of the URL? The original var controller_to_return_to looks like this when sent through the "Sure you want to delete?" URL:
new_controller_index = max(loc for loc, val in enumerate(controller_to_return_to) if val == '/') # First find the last slash in the string
extra_controller = controller_to_return_to[(new_controller_index+1):] # strip off extra URL characters. Looks hacky.
form = FORM.confirm('Sure you want to delete this comment?',{'Back':URL(extra_controller)})