Applications that are using DirectFB can only run as root. The reason is that DirectFB can not write to /var/log/directfb for logging it's output.
I discovered this using vdr with vdr-xineliboutput and vdr-softdevice on a framebuffer for the Matrox G550 grahpics card.
I'm not sure how to solve this, but definitely i don't want to run vdr as root. I simply made /var/log writable for a group vdr is in.
dev-libs/DirectFB does not even *create* /var/log/directfb. As such, setting proper permissions for custom log directories is not an ebuild problem, sorry.
I checked again, this is configured in /etc/directfbrc and yes, it can be configured to be at a writable location such as /var/vdr.