protected override void txtID_KeyDown(object sender, KeyEventArgs e) { TextEdit textEdit = (TextEdit)sender; if (e.KeyCode == Keys.Return | e.KeyCode == Keys.Tab) { DIC_NATIONALITY dICNATIONALITY = new DIC_NATIONALITY(); if (this.m_Status == Actions.Add) { if (dICNATIONALITY.Exist(textEdit.Text)) { this.Err.SetError(textEdit, "Mã đã tồn tại."); textEdit.Focus(); } } } }