public event EventHandler OnCardButtonClick;

private void onCardButtonClick(object sender, EventArgs e)
{
    EventHandler CardButton = OnCardButtonClick;
    if (CardButton != null)
    {
        CardButton(this, e);
    }
}

private void AddButton()
{
    OKButton.FontColor = BColor;
    OKButton.Location = new Point(210, InfoLabel.Location.Y + InfoLabel.Height + 26);
    OKButton.Size = new Size(69, 33);
    OKButton.Text = cardButton;
    OKButton.Click += onCardButtonClick;
}

[Category("Appearance")]
public string CardButtonText
{
    get { return cardButton; }
    set
    {
        cardButton = value;

        OKButton.Text = cardButton;
        Invalidate();
    }
}