Actually detail explaination here :) I have no clue how this works either. How do you compress the runtime files? I managed to compress a .pz3 file I was saving and rather than it being 60K kb, it was just over 9K kb in size. There is something in that option that says "run python" something or other. All I did was check the box "use file compression" and didn't touch the python button, then clicked OK. Do I have to do something else to compress the library files because I don't notice a difference in disk space at all.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi