private void Btn_Edit_Click(object sender, EventArgs e)
 {
     if (CURRENT_DOCUMENT != null)
     {
         FormDocumentCU form = new FormDocumentCU(this, CURRENT_DOCUMENT);
         form.Show();
     }
 }
        private void Btn_Register_Click(object sender, EventArgs e)
        {
            FormDocumentCU createForm = new FormDocumentCU(this);

            createForm.Show();
        }