public void ShowEditor(ThemeCustomInfo theme) { var resize = ThemePage == null; FindName("ThemePage"); ThemePage.Load(theme); if (resize) { MainColumn.Width = new GridLength(ActualWidth, GridUnitType.Pixel); var view = ApplicationView.GetForCurrentView(); var size = view.VisibleBounds; view.TryResizeView(new Size(size.Width + 320, size.Height)); ApplicationView.PreferredLaunchViewSize = new Size(size.Width, size.Height); MainColumn.Width = new GridLength(1, GridUnitType.Star); } }