Grid combo filter by text instead of value

Hi,

The combo filter in a grid default shows the value of the options in the grid.
Is there a way to get the text in the combo.

I tried the following approach:

function RPRO()
{
	grid.attachEvent("onCollectValues",collectComboValues);
	grid.attachEvent("onFilterStart",filterGrid);
	grid.attachHeader("#text_filter,,#select_filter,#text_filter,#text_filter,#combo_filter,");
	grid.setSizes();
}

function collectComboValues(index){
        if (index==5){
        
            var c={}; var f=[];
           
            for (var i=0; i<this.getRowsNum(); i++){
                this.render_row(i);
                var text=this.cellByIndex(i,5).getTitle();
                c[text]=true;
            }
        
           for (d in c) 
              if (c[d]===true) f.push(d);
            
           return f.sort();
        }
    }
 
  
    function filterGrid(indexes,values){
        var i=indexes.indexOf(5);
        if (values[i]){
            var combo=grid.getFilterElement(5);
            var combo_value=combo.getOptionByLabel(values[i]).value;
	    alert("COMBOVALUE: " + combo_value);
            this.filterBy(5,function(value){
                return (value.toString().toLowerCase()==combo_value.toString().toLowerCase()); 
            });
            return false;
        }
        return true;
    }

But the variable value returns the value and combo_value returns the text.

Unfortunately it is not available to change the behavior of the combo filter to the described one. Combo filter works with the cell values only.