A new feature found in 4D 2004.1, you can turn on or off the deletion control mechanism of subforms. In 4D 2004, users can delete subrecords in a subform simply by using the Del or Backspace keys. Since this default behavior (in 4D 2004) can have unintended results on the interface design for certain applications (based, for instance, on buttons), you can prevent it thanks to the new Allow Deletion option, located in the subform properties ("Sub-Form" theme):
When this option is checked, the user will be able to delete subrecords using the Del or Backspace keys. When this option is un-checked, the Del and Backspace keys will not delete the subrecords.