I've come to the conclusion that a saved Site Template (Solution) cannot be edited. But I came across some articles that alluded to taking the WSP file off-line and hacking on it. So I went to "Save" it and SP says I have to deactivate it first. Figuring no one would be trying to create a new site in the next few minutes it would take me to save it, I tried to deactivate it. Then I get the warning that if I deactivate it existing sites spawned from the template will lose functionality.
What are they talking about?