How to move panels up/down on keysDown event in c#

I've 4 panels, having same Y and different X, that are created at the program start on a picturebox. When I click on a panel, it sets the focus and is ready to get a keysDown event so i.e. if I click on up arrow key the panel moves up. At the moment I've two problems:

1. panels don't redraw when Y changes


2. clicking on different panels produce a loop of actions: i.e. if I click 1 time on panel4, then 1 time on panel1 and then again 1 time on panel4 when I try to move it up or down it does the action more than 1 time so instead of move by 10 it really moves by 30..

This is the code:

public partial class FormView : Form
{
    List<CircleButton> myPanels = new List<CircleButton>(); // array of panels CircleButton
    Point[] arrayPoints_milestones; // array of X,Y
    int index;

    public FormView()
    {
        InitializeComponent();

        arrayPoints_milestones = new Point[4];
        for (int i = 0; i < 4; i++ )
        {
            arrayPoints_milestones[i] = new Point { X = 20, Y = 20 };
        }

        test();
    }

    protected void panel_Click(object sender, EventArgs e)
    {         
        CircleButton panel = sender as CircleButton;

        index = (int)panel.Tag;

        myPanels[index].Focus(); //panel.Focus();
        myPanels[index].PreviewKeyDown += new PreviewKeyDownEventHandler(panel_KeyDown);
    }

    private void panel_KeyDown(object sender, PreviewKeyDownEventArgs e)
    {         
        if (e.KeyCode == Keys.Up)
        {               
            arrayPoints_milestones[index].Y -= 10;
            //debug
            MessageBox.Show("" + arrayPoints_milestones[index].Y);

            Invalidate();
        }
        if (e.KeyCode == Keys.Down)
        {
            arrayPoints_milestones[index].Y += 10;
            //debug
            MessageBox.Show("" + arrayPoints_milestones[index].Y);

            Invalidate();
        }            
    }

    private void test()
    {
        //for (int i = 0; i < 4; i++)
        int i=0;
        foreach(var value in arrayPoints_milestones)
        {
            CircleButton panel = new CircleButton();
            panel.Name = "panel" + i;
            panel.Tag = i;
            panel.Centre = new Point(arrayPoints_milestones[i].X + i * 10, arrayPoints_milestones[i].Y);
            panel.Radius = 10;
            panel.BackColor = Color.Red;
            panel.Message = "Index: " + panel.Tag.ToString();

            myPanels.Add(panel); 

            pictureBox1.Controls.Add(myPanels[i]);
            myPanels[i].Click += new EventHandler(panel_Click);

            i++;
        }
    }
}

and this is the custom panel class:

public class CircleButton : Panel
{
    //Properties to draw circle
    float radius;
    public float Radius
    {
        get { return radius; }
        set
        {
            radius = value;
            this.Size = new Size((int)Radius, (int)Radius);
        }
    }

    public string Name
    {
        get;
        set;
    }

    Point centre;
    public Point Centre
    {
        get { return centre; }

        set
        {
            centre = value;
            this.Location = Centre;
        }
    }

    public string Message { get; set; }

    public CircleButton()
    {
        //Default Values
        Name = "panel_base";
        this.BackColor = Color.Black;
        Radius = 1;
        Centre = new Point(0, 0);
        this.DoubleBuffered = true;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);

        //Defines a graphic path and set it as the panel's region
        //For custom region use different path's
        if (centre != null)
        {
            GraphicsPath path = new GraphicsPath();
            path.AddEllipse(0, 0, radius, radius);
            this.Region = new Region(path);
            path.Dispose();
        }
    }        
}