after emerging nvidia-drivers-169.09-r1 a link is created from /usr/lib/xorg/modules/extensions/libwfb.so to /usr/lib/opengl/nvidia/extensions/libwfb.so which doesn't exist.
X tries to load the modules and fails.
Reproducible: Didn't try
I created a link to /usr/lib/opengl/nvidia/extensions/libnvidia-wfb.so.169.09 instead.
My first bug report, please don't blame ;)
*** This bug has been marked as a duplicate of bug 202978 ***