get visible columns of UltraWinGrid

/// <summary>
     /// Exports all the Visible Columns from an UltraGrid to Excel
     /// If you are looking at above C# 3.5 then refer Microsoft.CSharp Assembly in your project references
     /// </summary>
     /// <param name="Grid">UltraGrid</param>
     public static void ExportToExcel(this UltraGrid Grid)
     {
         if (Grid == null || Grid.Rows.Count == 0) return;

         var xlApp = new Excel.Application();
         try
         {
             System.Windows.Forms.Cursor.Current = System.Windows.Forms.Cursors.WaitCursor;

             List<String> Columns = new List<string>();

             ///Setting the Current Culture...Can remove this
             Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");

             Excel.Workbooks workbooks = xlApp.Workbooks;
             Excel.Range range;
             Excel.Workbook workbook = workbooks.Add();
             Excel.Worksheet worksheet = workbook.Worksheets[1];

             long totalCount = Grid.Rows.Count;
             long rowRead = 0;

             UltraGridColumn column = Grid.DisplayLayout.Bands[0].Columns[0];

             /// Get the next visible column by passing in VisibleRelation.Next.
             column = column.GetRelatedVisibleColumn(VisibleRelation.First);

             while (null != column)
             {
                 Columns.Add(column.Key);

                 /// Get the next visible column by passing in VisibleRelation.Next.
                 column = column.GetRelatedVisibleColumn(VisibleRelation.Next);
             }


             ///Create Columns Object and Select those Columns only
             for (var i = 0; i < Columns.Count; i++)
             {
                 UltraGridColumn Column = Grid.DisplayLayout.Bands[0].Columns[Columns[i]];

                 worksheet.Cells[1, i + 1] = Column.Header.Caption;
                 range = (Excel.Range)worksheet.Cells[1, i + 1];
                 range.Interior.ColorIndex = 20;
                 range.Font.Bold = true;
             }

             ///Now fill in the Rows to Excel
             for (var r = 0; r < Grid.Rows.Count; r++)
             {
                 for (var i = 0; i < Columns.Count; i++)
                 {
                     UltraGridColumn Column = Grid.DisplayLayout.Bands[0].Columns[Columns[i]];

                     if (Column.Format != null)
                     {
                         ///If you have defined Specific formats and would like them to be part of the excel
                         ///then you can customize as below
                         if (Column.Format.Equals("##,###") || Column.Format.Equals("#,##"))
                         {
                             worksheet.Cells[1, i + 1].EntireColumn.NumberFormat = "#,###;(#,###);-";
                             worksheet.Cells[r + 2, i + 1] = Grid.Rows[r].Cells[Columns[i]].Value;
                         }
                         else if (Column.Format.StartsWith("##,###.##") || Column.Format.Equals("#,##.##"))
                         {
                             worksheet.Cells[1, i + 1].EntireColumn.NumberFormat = "#,##0.00;(#,##0.00);-";
                             worksheet.Cells[r + 2, i + 1] = Grid.Rows[r].Cells[Columns[i]].Value;
                         }
                         else if (Column.Format.StartsWith("MM/dd/yyyy"))
                         {
                             worksheet.Cells[1, i + 1].EntireColumn.NumberFormat = "MM/dd/yyyy";
                             worksheet.Cells[r + 2, i + 1] = Grid.Rows[r].Cells[Columns[i]].Value;
                         }
                         else
                         {
                             worksheet.Cells[r + 2, i + 1] = Grid.Rows[r].Cells[Columns[i]].Value;
                         }

                     }
                     else
                     {
                         worksheet.Cells[r + 2, i + 1] = Grid.Rows[r].Cells[Columns[i]].Value.ToString();
                     }
                 }

                 rowRead++;
             }

             Microsoft.Office.Interop.Excel.Range columns = worksheet.UsedRange.Columns;
             columns.AutoFit();

             ///Display the Excel Component to User
             xlApp.Visible = true;
         }
         catch (Exception ex)
         {
             System.Windows.Forms.Cursor.Current = System.Windows.Forms.Cursors.Default;
             System.Windows.Forms.MessageBox.Show("Exception occured while exporting rows to Excel. Exception Details : " + ex.Message.ToString(), "Excel Export", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Information);
         }
         finally
         {
             ///Force Clean up the Com Component to remove any traces
             GC.Collect();
             GC.WaitForPendingFinalizers();
             foreach (Excel.Workbook wb in xlApp.Workbooks)
             {
                 foreach (Excel.Worksheet ws in wb.Worksheets)
                 {
                     Marshal.FinalReleaseComObject(ws);
                 }
                 wb.Close(false, Type.Missing, Type.Missing);

                 Marshal.FinalReleaseComObject(wb);
             }
             xlApp.Quit();
             Marshal.FinalReleaseComObject(xlApp);

             System.Windows.Forms.Cursor.Current = System.Windows.Forms.Cursors.Default;
         }
     }