ui.Dialog.getSortKey
Returns the name of the sort field selected by the user.
Syntax
getSortKey(
   name STRING )
  RETURNS STRING
- name is the name of the screen record, see Identifying screen-arrays in dialog methods.
 
Usage
The getSortKey() method returns the form field name selected by
 the user to sort rows.
This method is used in the context of the 
ON SORT trigger.
 Note: If the sort is reset, the 
getSortKey() method returns
 NULL.