nvidia updated the driver for Linux to be compatible with Xorg 1.18( which is ABI incompatible to the previous version )

Today I got a hint, that nvidia has updated the driver to version 340.96 for linux 64 bit, with
support for Xorg 1.18.

Xorg 1.18 had an ABI incompatibility to the previous version, so I can upgrade the Xorg packages  back to the repos of Fedora 23.
Installing the new nvidia driver and the Gnome Desktop is back again.

( http://www.nvidia.com/download/driverResults.aspx/95165/en-us )