>when is the right time to call InitializeComponent();?
>
>

>
>     public Window1()
>        {
>
>            HolePatterns = new ObservableCollection<HolePattern>();
>            HolePatterns.CollectionChanged += new NotifyCollectionChangedEventHandler(HolePatterns_CollectionChanged);
>
>            CurrentHolePattern = new HolePattern();
>            CurrentHolePattern.PatternName = "Test Pattern Name";
>
>            //-- Set some default values for the UI
>            CurrentHolePattern.BoltCirDia = 12.0;
>            CurrentHolePattern.HoleCount = 6;
>            CurrentHolePattern.StartAngle = 0;
>
>            HolePatterns.Add(CurrentHolePattern);
>
>            InitializeComponent();
>
>            SketchX0 = canvas1.Width / 2;
>            SketchY0 = canvas1.Height / 2;
>            SketchBoltCirRad = canvas1.Width / 2 * .7;
>
>
>            CoordinateGrid.ItemsSource = CurrentHolePattern.HoleList;
>
>            RedrawScreen();
>
>
>        }
>

Where you are calling it is fine. You need to call it before you can reference any item in XAML.