Hi,

I just add the opportunity to look back at the old Studio 5.0.x, and the Read-Only flag in the Open dialogue didn't have a registry value that would it make "sticky".

I remember once coming up with an approach by using the GetStatus() method on a class extending  %Studio.SourceControl.Base:

one of the supported parameters is "Editable", where you could set this to 0 inside of this method to prevent editing of the open item.

Not really a direct solution to your question, but if you happen to already be using Studio hooks, it may be worth a look.

HTH