Threesome

Jussi Pakkanen has released Why beta 3:

Scripting has been improved quite a lot and the release now has in-depth documentation on the subject.

Binaries are available for both Linux and Windows. Since this DOOM level editor is distributed under the Gnu General Public License, you can also have a look at its source code. Note that Jussi has added a 'How to help the development of Why' section to his site: don't miss it, and remember you can use the feedback form to help tracking bugs.