+1 for this feature.
It would be really handy to have this feature, maybe like a dropdown or something alike, to shutdown after performing backup via "Backup now"-Button.
Of course it is good to ignore the post job action for backup-now, but it would be nice to be able to shut down the computer after performing backup-now-action.
Some of our customers don't have fixed closing times in their offices, so the planned-task-option isn't very useful for these situations.
Of course post job actions are a great, but in some cases they are not practical.