Hello, I have a question about good coding practices. I have a NSTreeController binded to a NSManagedObjectContext, which works fine. The NSArrayController is binded to the selection of NSTreecontroller. For single selections, everything works fine. But when the selection is zero or multiple the NSArrayController has to return different values, also depending on what is selected. The problem is that my subclass of NSArrayController complete ignores my code, and goes straight the the NSManagedObjectContext and gives the standard reply of Empty Selection and Multiple Values.