It's also not just a GUI. There is loads of code in there that does stuff. For example:
• Scheduling for scheduled backups
• A background daemon that looks for events to launch the UI for scheduled backups
• Manipulation of disks ownership stuff in order to allow backups with permissions to happen correctly
• Volume blessing, etc, in order to make bootable volumes
• Trash handling & maintenance for deleted files
• Deleting files (for removing old backups)
And that was just off the top of my head. The app is many thousands of lines of code and it performs literally hundreds of functions. They're nearly all transparent to the user, and that is the idea.
• Scheduling for scheduled backups
• A background daemon that looks for events to launch the UI for scheduled backups
• Manipulation of disks ownership stuff in order to allow backups with permissions to happen correctly
• Volume blessing, etc, in order to make bootable volumes
• Trash handling & maintenance for deleted files
• Deleting files (for removing old backups)
And that was just off the top of my head. The app is many thousands of lines of code and it performs literally hundreds of functions. They're nearly all transparent to the user, and that is the idea.