In order to install the modular xserver-xorg (1:7.0.2) I had to remove the old xserver-xorg and xserver-common (6.9.0.dfsg.1-4). Some dependency error here in the upgrade (reported before). Additionally the font paths are wrong in the created xorg.conf file when configuring the server!!! Fonts are located at /usr/share/fonts/X11/... not /usr/share/X11/fonts/...