Protecting a StackRunner (or Player) stack

[rand valentine]

 Hi, all. I've been making some really fun language learning/teaching
materials using Rev Studio 2.7.2 on my Mac running OS 10.4.7. I greatly
prefer to distribute my stuff (in other words, make it available to
students) by just using StackRunner, rather than making standalones, which
always seems to entail untold headaches. But since my stacks are
preliminary, I want to write an expiration date into them, e.g., one obvious
way to do this is check the date in a preopenstack handler, and if it's past
a certain date, just cause the stack to quit. But is there any way to
protect that preopenstack from prying eyes? Note that the students interact
with the stacks _a lot_, so I need the stacks to be totally "editable" in
the sense of being able to add data to text fields, click on buttons and
change settings, etc. So is there any easy way to protect a script? Thanks.

rand valentine