how i wpf polygon vertex circles

Question

 Polygon p = new Polygon();
            p.Stroke = System.Windows.Media.Brushes.Black;
            p.Opacity = 0.5;
            p.Fill = System.Windows.Media.Brushes.LightBlue;
            p.StrokeThickness = 1;
            p.HorizontalAlignment = HorizontalAlignment.Left;
            p.VerticalAlignment = VerticalAlignment.Center;


            //Left Up, Right Up, Left Down, Right Down
            p.Points = new PointCollection() { new System.Windows.Point(0, 0), new System.Windows.Point(100, 0), new System.Windows.Point(100, 100), new System.Windows.Point(0, 100) };
            canvas.Children.Add(p);

this is my code, just draw 4 points polygon

i want make draw circle on polygon vertex.. because i will be edit polygon with points drags

but vertex point is very small

i see that on winform when draw polygon have vertex circle

look like this

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