Now I know some more:
I hadn't had a config.cfg file in the 2.4 dev-version. I had one in the 2.3 version, but in the 2.4 dev-version, on the place where the config.cfg, the stats.log file etc. should be, there was only the ufoconsole.log. Perhaps that's the problem?
I thought myself clever and tried out if it worked with the config.cfg-file from 2.3 with the cl_introshown set to 1. This time, it was on the whole screen and not only in a window, but it crashed the same moment as always.
PS @ Damonicos: Spotlight is the search in your mac. In every Finder-window it's in the upper right corner and it's on the upper right corner of your screen (the magnifying glass).