private void checkInButton_Click(object sender, EventArgs e)
        {
            CustomerCheckIn form = new CustomerCheckIn(Model);

            form.Dock = DockStyle.Fill;
            form.MdiParent = this.MdiParent;
            form.Show();
            form.WindowState = FormWindowState.Maximized;
        }
 private void button6_Click(object sender, EventArgs e)
 {
     CustomerCheckIn customerCheckIn = new CustomerCheckIn(Model)
     {
         Dock = DockStyle.Fill,
         MdiParent = this.MdiParent
     };
     customerCheckIn.Show();
     customerCheckIn.WindowState = FormWindowState.Maximized;
 }