If you run the following and then scroll to the right, the merged columsn don't scroll as I would expect. They are static at the top and only the row below moves as I would expect.
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].ColumnsCount = 0;
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].RowsCount = 0;
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddRow();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddRow();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].AddColumn();
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Merge(0, 1, 0, 4);
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[0, 1].Value = "Merge Column #1";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Merge(0, 5, 0, 8);
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[0, 5].Value = "Merge Column #2";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 0].Value = "";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 1].Value = "1";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 2].Value = "2";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 3].Value = "3";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 4].Value = "4";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 5].Value = "5";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 6].Value = "6";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 7].Value = "7";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].Cells[1, 8].Value = "8";
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].FrozenCols = 1;
ActiveGridDesktop.Worksheets[ActiveGridDesktop.ActiveSheetIndex].FrozenRows = 1;