/// <summary>
        /// Cancel button event
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonCancel_Click(object sender, EventArgs e)
        {
            FormDialogCancel formDialogCancel = new FormDialogCancel();

            if (formDialogCancel.ShowDialog(this) == DialogResult.Yes)
            {
                this.DialogResult = DialogResult.Abort;
                this.Close();
            }
        }
        /// <summary>
        /// Cancel button event
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void buttonCancel_Click(object sender, EventArgs e)
        {
            Form dialogCancel = new FormDialogCancel();

            if (isGraphChanged)
            {
                if (dialogCancel.ShowDialog(this) == DialogResult.Yes)
                {
                    this.DialogResult = DialogResult.Abort;
                    this.Close();
                }
            }
            else
            {
                this.DialogResult = DialogResult.Abort;
                this.Close();
            }
        }