By pure coincidence I found some files in Koala-Paint format. Since Koala-Paint was the first drawing tool I ever used (must be back in '82) a fit of nostalgia hit me. I started the Gimp and tried to read the files which the program politely refused. Finding some information on the Koala-Paint format wasn't that difficult and within a few minutes it all came back. I remembered exactly how the Commodore 64 graphics memory was organized. One hour later the next picture appeared on the screen:

Building the plug-in is straightforward. First unpack the gzipped tarfile:

 % tar xvfz koala-0.9.tgz

Next compile and install the plug-in with:

 % gimptool --install koala.c