I'm trying to get a color coded world in minecraft, and i looked up a NBTExplorer tutorial to do so. I double clicked on the LevelName: file and nothing popped up. I downloaded the mac version, but it still won't open. Any help please?
You have to open NBTExplorer and open the file from there with the leftmost icon in the tool bar.
Just double clicking an NBT file is a good idea, but it's currently not implemented.