Deleting a partition or files does not guarantee that the data cannot be recovered by new users of the disk. Inexperienced users might expect this when deleting a partition, giving them a false sense of security.

Applying deletion of a partition should provide an ignorable notification that data might be recovered by new users of the disk for malicious purposes. A reference should be made to overwrite an entire disk with random data to effectively shred the contents of the disk.

Gparted should offer functionality to execute
  time dd bs=1024k if=/dev/urandom of=/dev/sdb
as described by http://www.duncanelliot.com/blog/?p=7

During shredding of the disk, an animated pop-up should inform the user that the disk shredding process is running and that it can take a /while/. Perhaps a simple estimate based on CPU speed and disk size can also be given. Of course the user should be asked if he or she would really, really, really like to shred the disk. Optionally, this could also be offered for separate partitions.

Implementing this feature will increase security by preventing malicious recovery.