public MainWindow()
{
EventManager.RegisterClassHandler(typeof(Window), Keyboard.KeyUpEvent, new KeyEventHandler(keyUp), true);
MemoryStack = new Values();
InitializeComponent();
InitializeCalculationMode();
UpdateDisplays();
}
// Constructors(s)
public XRegister(Values parentStack)
{
ParentStack = parentStack;
NewEntryBuffer = "";
}