onListBeforeSelect

fires before an item selection started

boolean onListBeforeSelect(string itemId,boolean selection,object list){ ... };

itemId	string	the item id
selection	boolean	true - to select, false - to unselect
list	object	the list that contains the item

boolean

if the event handler returns false, the item will not be selected

$$("myBoard").attachEvent("onListBeforeSelect", function(itemId,selection,list){
    // your code
});