Indeed, thanks for the quick reply.
To comply with the request of dominikbodi the EULA has been removed and the user is not anymore required to accept the GNU licence before running the software. Of courses the sources are still released under this license according to the terms stated on Sourceforge.
P.S. the phase "I would keep my hands off that software" looks a bit extreme isn't it? ;) Especially considering that the software has been downloaded and used by over 500K people in the past 5 years.
The issue above has been resolved.
IANAL etc. but I would keep my hands off that software:
1. The author requires the user to accept the GPL before using the software. However, the GPL states that agreement to the license is not necessary for the purpose of simply running the program. Agreement to the GPL is required only for performing all other activities by the license.
2. The user has to agree to additional licensing terms written down in an extra EULA. The provisions in the EULA conflict with the GPL, particularly the provisions in the EULA requiring the user to agree not to use the software for certain purposes. Most of those provisions are redundant, as most of those activities prohibited in those are illegal in most countries anyway.
3. The Section 7 of the GPLv3 restricts the restriction an author may apply to his or her software. It does not matter if those restrictions are written down in a separate license or not.
The author's intent is unclear, as both the GPL and the EULA contradict each other. The author should contact the FSFE Freedom Task Force in order to resolve the licensing issues: http://www.fsfe.org/projects/ftf/ftf.en.html
An open, cross-platform journaling program.
A scientific plotting package.