[Closed] Callback script: pre render abort

I’m working on a little script to help me to remember to unhide needed geometry before I send a big render/animation. I can’t figure out how to actually abort a render once the render has begun. The result of this code (if something is hidden) is that the query box shows up, and I can hit no till I’m blue in the face, or yes about 12 times before it actually renders.
Also, We use brazil SFNDR a lot here, and that script doesn’t appear to use the same render() function as the usual render dialog. Any ideas? I’m out of town starting tomorrow afternoon (thurs Sep 21) for 10 days, so if the post doesn’t get any responses before noon tomorrow (MST), I won’t check till I’m back.

fn isHidden =
  (
  	global sceneNodes = $* as array
  	hiddenElements = for obj in sceneNodes where obj.ishidden == true collect
  	while hiddenElements != undefined do 
  		(
  		YayNay = querybox "Something is hidden. Render Anyway?"
  		if yayNay == true then exit  --this is the line that needs some help
  		)
  )
  callbacks.addscript #preRender "isHidden()"