|Problem: stage 6 creates strange assignments on left hand side
[self cell] = newCell; // because "cell" was a private
// ivar of superclass
Solution: Use only methods provided in API. Exp:
Problem: Program crashes when reading defaults
Solution: Remove old defaults, and move to new model.
Problem: Program crashes when setting popup's title
Solution: In IB, connect the popup outlet to the button itself.
In 3.x, you had to pop-up list and connect to the matrix,
now you just connect to the NSButton object.
Problem: Program crashes when accessing stored defaults array
Solution: If you store an array to the NSUserDefaults database, you must retrieve it with "arrayForKey:" even though you stored it with setObject:forKey:. When you retrieve it via "objectForKey:", it comes back as an NSString, which is not what you want.