Sorts the list items based on
#getSortAscendingand
#getSortDescending, if
#getSortDirection doesn't
matches the ascending argument.
It checks
#getSortDirection to see whether sorting
is required, and update
#setSortDirection after sorted.
For example, if
#getSortDirection returns "ascending" and
the ascending argument is false, nothing happens.
To enforce the sorting, you can invoke
#setSortDirectionwith "natural" before invoking this method.
Alternatively, you can invoke
#sort(boolean,boolean) instead.
It sorts the listitem by use of
Components#sortdata (i.e.,
Grid#getModel is null).
On the other hand, it invokes
Sortable#sort to sort
the list item, if live data (i.e.,
Listbox#getModel is not null).
In other words, if you use the live data, you have to implement
Sortable to sort the live data explicitly.