onItemCheck

fires when you check an item in tree and treetable

void onItemCheck(id id,boolean state,Event e);

id	id	the ID of the related item
state	boolean	defines the checked/unchecked state of a checkbox
e	Event	a native event object (absent when the threeState property is enabled)

some.attachEvent("onItemCheck", function(id, state, e){
    //... some code here ... 
});