/// <summary>
        /// Open the form inside this.form.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void btnAssembly_Click(object sender, EventArgs e)
        {
            FrmAssembly assembly = new FrmAssembly();

            assembly.ChangeForm += this.ChangeChildAssemble;
            OpenChildForm(assembly);
        }
        /// <summary>
        /// Changes the active child form.
        /// </summary>
        public void ChangeChild()
        {
            this.btnAssembly.Enabled = true;
            ButtonAssemblyFormat();
            FrmAssembly assembly = new FrmAssembly();

            assembly.ChangeForm += this.ChangeChildAssemble;
            OpenChildForm(assembly);
        }