if (current.col > mergeParent.col) { //entering merge by going up or left
        if (!this.lastDesiredCoords) {
          this.lastDesiredCoords = new WalkontableCellCoords(current.row + delta.row, current.col + delta.col); //copy
        }
        delta.col += (mergeParent.col - current.col) - delta.col;