class CustomMergeManager extends wjGrid.MergeManager {
  getMergedRange(panel, r, c, clip = true) {
    //
    // create basic cell range
    var rng = new wjGrid.CellRange(r, c);
   if ( panel.cellType === wjGrid.CellType.ColumnHeader || panel.cellType === wjGrid.CellType.TopLeft) {
///// 추가할 코드 시작 
     // expand left/right
        for (var i = rng.col; i < panel.columns.length - 1; i++) {
            if (panel.getCellData(rng.row, i, true) != panel.getCellData(rng.row, i + 1, true))
                break;
            rng.col2 = i + 1;
        }
        for (var i = rng.col; i > 0; i--) {
            if (panel.getCellData(rng.row, i, true) != panel.getCellData(rng.row, i - 1, true))
                break;
            rng.col = i - 1;
        }
///// 추가할 코드 끝