jQuery Grid Plugin - jqGrid

In Jqgrid - inline editing functionality ; how do i determine that selected row is actually edited by the user

The below code will try to save all the rows which have been selected by user prior to another rows selection.

and i want the only rows that have been edited not just selected.

jQuery("#grid_id").jqGrid({
...
   onSelectRow: function(id){
     if(id && id!==lastSel){ 

        jQuery(this).saveRow(lastSel, true, 'clientArray');

        lastSel=id;

     }
     jQuery('#grid_id').editRow(id, true);
   },
...
});