onBeforeContextMenu

fires before the context menu is called in the item area

boolean onBeforeContextMenu(string id,Event e,HTMLElement node);

id	string	the id of the clicked item
e	Event	a native event object
node	HTMLElement	the target HTML element

boolean

returning false will block the event

Example

$$("list").attachEvent("onBeforeContextMenu", function(id, e, node){
     if (some_check(id)) 
          return false; // blocks the context menu
     else 
          return true;
});

Details

Returning false from the event handler will block further processing.