Update(Début-Tp3): Color

Sources/WpfApp/MainWindow.xaml.cs

@@ -380,7 +380,7 @@ namespace WpfApp
                 {
                     Width = CircleStartSize,
                     Height = CircleStartSize,
-                    Fill = Brushes.Red,
+                    Fill = Brushes.Purple,
                     Opacity = 0.5
                 };