How to make files in working tree RO automatically

[Simon Kersey]

Hi,

I'm trying to automatically make certain files in a working tree RO when it is 
created.  I can do this for heavyweight branches and checkouts using a branch 
open hook. However for lightweight checkouts the branch does not correspond to 
the working tree.  I have tried using the bzrdir pre-open hook but this does 
not seem to be called with a transport that reflects the working tree when 
performing a lightweight checkout.

Is there a better hook to use or better way to do this?

Any suggestions would be much appreciated.

Cheers,

Simon