Hi, Valentime Blacker.
The map editor has not worked in the last few releases. I had not had a use for it since it was made, and hadn't recieved any feedback on it, so it fell into disrepair. Instead, I've been finding that Tiled Map Editor does everything I've needed for my projects.
There are likely other things wrong with it besides the Map import. For example, the supporting functions in the toolkit module to import and export map data are most assuredly broken.
The only purposes I can intuit for the map editor are: 1) mapping polygons (other than axis-aligned rectangles) for pymunk; 2) mapping polygons (other than axis-aligned rectangles) for use with the gemoetry module's collision functions. If someone has a real project use for these, I'll consider keeping the map editor. But right now it is just a curiosity that I poured a lot of time into and gotten little in return.
Also, if someone sends me a fix I'll gladly include it. :)
I highly recommend checking out Tiled Map Editor, and DR0ID's pytmxloader library which decodes Tiled maps for pygame (and pyglet). The latest release of DR0ID's library has some very nice examples that demonstrate how well it stands on its own, and provide some valuable insight into just what Tiled Map Editor brings to the table.
All that said, I am also happy to take feedback and requests about Gummworld2 and the editor.
Cheers.
Gumm