I've been trying to export my greenfoot game for about 3 hours but I can't get it to work. github link this is the github page if the game, I am working in an external ide so that's why I am able to work in packages. it also fully functions in greenfoot. I think greenfoot doesn't know what the default world is when you execute the exported jar because it creates an empty window. anyways, does somebody here know why this is happening. I am using version 3.1 btw, in the newer versions there is no good way of using an external ide.