If you have OpenSSH installed FileBox would only need to pass the command through xterm/bash/ash. And the file would be sent to the folder on the host computer. (if you have chosen a preconfigured folder)

So if you make a note that OpenSSH needs to be installed for scp support. You would not need the dependecy and keep FileBox a bit slimmer for those who are not using scp. Though many of us do. Though i do not think the added support would make the install file a lot bigger.

A better way.. and preferred if you want to fetch a file. Is to have support for it in the "adress field". And with a auto-complete function or some sort of bookmark feature. Sometimes a scp string can get very long.