That NSOpenPanel class reminds me of MFC days. For those young enough to remember, it's Microsoft Foundation Classes, the UI framework for Windows. Everything

That NSOpenPanel class reminds me of MFC days. For those young enough to remember, it's Microsoft Foundation Classes, the UI framework for Windows. Everything had to be a class in MFC: new window - a class, file open dialog - a class. In order to understand what you code does, you have to analyze the whole hierarchy of classes, and figure out where that particular virtual method that you need is implemented. Deep inheritance hierarchies of MFC coined the term "fragile base class" problem where changes to a base class can inadvertently affect the behavior of derived classes, potentially causing them to malfunction or behave in unexpected ways.