Current questions and answers regarding the map editor.

I want to play with a friend using a specific setup. But there's a problem: I created a map that's 48 KB in size, and it needs editing. After editing, the file size is 1 KB. I saved it as a new file and overwrote the existing one, but the result is still 1 KB. The "original" version is available. How can I properly save the edited version? P.S. The original version works fine.