private void OnAddDicomTagClick(object sender, EventArgs e)
        {
            try
            {
                ushort group   = ushort.Parse(_txtDicomTagGroup.Text, NumberStyles.AllowHexSpecifier);
                ushort element = ushort.Parse(_txtDicomTagElement.Text, NumberStyles.AllowHexSpecifier);
                uint   tag     = (uint)(group << 16) + element;

                StudyFilterColumn.ColumnDefinition column = StudyFilterColumn.GetColumnDefinition(tag);
                if (_lstSelectedColumns.Items.Contains(column))
                {
                    return;
                }

                _lstSelectedColumns.Items.Add(column);
                _component.Columns.Add(column);
            }
            catch (FormatException) {}
        }