x11/nvidia-driver incompatible with portmaster?

[Stephen Montgomery-Smith]

Are x11-server/x11-server and x11/nvidia-driver together incompatible 
with portmaster?

If you install x11-server/xorg-server, and then install 
x11/nvidia-driver, then "pkg_delete -f" and reinstall xorg-server, then 
it seems to me that x11/nvidia-driver will be broken, because 
xorg-server will overwrite lib/xorg/modules/extensions/libgl.*, and 
nvidia-driver also writes these files.

I know that x11/nvidia-driver restores the libgl.* files when it is 
deinstalled.  But it is portmaster's use of "pkg_delete -f" that 
concerns me.

Thanks, Stephen