The first attempt to get Flatpress 1.0.3 running under PHP 5.6 is solved with this quick and dirty patch:
Adding the PHP command “error_reporting” in these listed files:
defaults.php - error_reporting(0); login.php - error_reporting(0); admin/main.php - error_reporting(0);
Now you can running Flatpress 1.0.3 without errors and warnings. This is a quick solution for everyone without PHP programming expertise.