DISPLAY ARRAY modification triggers

Using dedicated interaction blocks to allow the user to modify a read-only record list.

The DISPLAY ARRAY block implements by default a read-only list of records. The end user can navigate in the list, but cannot modify the rows.

The traditional way to implement an editable list of record is to use INPUT ARRAY. However, INPUT ARRAY uses ergonomics that may not correspond to the end user expectations. Basically, a list controlled by an INPUT ARRAY is always in "edit mode": the focus is in a field and the user can modify the current field. When moving up or down in the list, the edit cursor jumps to the upper or lower cell.

Other GUI applications use a different pattern, with read-only lists that can switch to edit mode when a specific action is fired. To implement such ergonomics, use the ON INSERT, ON APPEND, ON UPDATE, ON DELETE modification triggers to control row insertion, appending, modification and deletion in a DISPLAY ARRAY block.