[gears-users] createWorkerFromUrl error

[skunkwerk]

Hi folks,
    i'm getting this error:
URL scheme 'file' is not supported.

when running this line:
var childWorkerId = workerPool.createWorkerFromUrl('scripts/
worker.js');

on Firefox 3 with Gears 0.5.21 on Mac OS X

the page gears is running on is a local file:
file:///Users/bourbaki/Code/eurisko/index.html

questions:
1)  am i doing something wrong, or is this feature not implemented
yet?  if the latter, could someone point me to the relevant code where
i could fix it?

thanks,
imran