[DefaultValue(typeof(Color), "Window")]
    public override Color BackColor
    {
        get {return base.BackColor;}
        set {base.BackColor = value;}
    }
    [DefaultValue(typeof(Color), "WindowText")]
    public override Color ForeColor
    {
        get {return base.ForeColor;}
        set {base.ForeColor= value;}
    }

In this case, the colors are assigned as a kind of "named" values.
How can I assign RGB values?