fnPreRowSelect does not work for button "select_all" - event is always null

edoarsla

I am not able to get select_all to NOT select certain tables. If I follow the example from the documentation, fnPreRowSelect works perfectly for selecting individual rows. However, when "select_all" button is used, event(e) is always null.

Here'e jsFiddle setup:
http://jsfiddle.net/9FjN5/2/

Allan, thank you for this amazing tool!