the attached example shows a case using select all in a listbox using the paging mold.

when selecting all:
in both events "onSelect" and "onCheckSelectAll" the model contains the expected selection of all items.

when un-selecting all:
the onSelect event shows a different state selected-set than the empty set when onCheckSelectAll is called.

this makes it difficult to implement an onSelect listener in general because it gives the false impression only 5 elements have been unselected.