How do you imagine that feature would work?
If you're always copying the same column(s), you could trivially add a
new context-menu item... e.g. Rules > Customize Rules, and add the
following:
public static ContextAction("Copy Hosts")
function CopyHostsToClipboard(oSessions: Session[]){
var s= "";
for (var x = 0; x < oSessions.Length; x++){
s += oSessions[x].hostname + "\r\n";
}
Utilities.CopyToClipboard(s);