close a source file
Why would you _ever_ do that? Now that we have tabs and the wonderful single-window display, I just leave everything open. Or you could minimize instead of closing.
Well, the beauty of great software is that it doesn't force everyone to use it the same way :)
Minimising wouldn't really work, I'm not trying to hide or move TM out the way. I'm developing a number of concurrent projects, some of which have hundreds of source files. You can see how this would easily become unmanageable if I tried to keep every file open.
If it works for you though, great :-)