private void dataGrid_content_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
if (e.ColumnIndex == dataGrid_content.Columns["btn_undo"].Index)
{
if (dataGrid_content.Rows[e.RowIndex].Cells[4].Value.ToString() != "Completed")
{
JournalTask.DataGridViewCellVisibility(dataGrid_content.Rows[e.RowIndex].Cells["btn_undo"], false);
}
}
}