Sub-Grid return other field

I have a main grid with a grid excell type that shows a directory tree.

When I loadxml for the main grid I pass the directory path which appears in the main grid cell.

When I serialize the tree the text value appears in the serial string.

When I select a value in the sub-grid it returns the text to the main grid cell as expected but when I serialize it serializes the sub-grid id number.

Is there a way to have the grid excell return a different cell instead of the cell id?

In dhtmlxgrid_excell_grid.js , replace
    this.getValue = function(){
        return this.cell._val;
    this.getValue = function(){
        return this.cell.innerHTML;

As result cell will return visible text as cell value instead of ID