[X4U] Prevent accidental unmounting?

[nk]

In a fit of I dunno what, I un-mounted another Mac which was  
connected to my main mac, and which was quite busy doing network 3D  
rendering. I was hoping I'd get one of those "Can not unmount the  
server because it's in use" things.

no such luck.

Aside from just hiding other computers in the sidebar, is there  
another way to protect myself from dumb mistakes like that?

nk