public abstract class SignPad : IDisposable
{
    protected SignPad();

    public bool Enabled { get; }
    public abstract string Lib { get; }
    protected bool enabled { get; set; }

    public virtual void Dispose();
    public abstract System.Drawing.Image GetSignature(System.Windows.Forms.Form owningForm, string msg);
    public virtual void OnEnabledChanged();
}