private static void MyColsProperty_Changed(DependencyObject d, DependencyPropertyChangedEventArgs e) { DesignerCanvas designerCanvas = (DesignerCanvas)d; int myCols = (int)e.NewValue; if (myCols > 0 && designerCanvas.MyRows > 0 && designerCanvas.ActualHeight > 0 && designerCanvas.ActualWidth > 0) { designerCanvas.BrushGrid(); } }