In editing mode you can't change one cell's value directly but you can extend an editor to simulate this action.
$.extend($.fn.datagrid.defaults.editors,{
label:{
init:function(container,options){
return $('<div></div>').appendTo(container);
},
getValue:function(target){
return target.value || $(target).html();
},
setValue:function(target,value){
target.value = value;
$(target).html(value);
},
resize:function(target,width){
$(target)._outerWidth(width);
}
}
});
$(function(){
$('#tt').edatagrid({
columns:[[
{field:'attr1',editor:'label',...}
]],
onEdit:function(index,row){
var ed = $(this).edatagrid('getEditor',{index:index,field:'attr1'});
// change the 'attr1' cell of the editing row
$(ed.target).html('<span style="color:red">'+row.attr1+'</span>');
}
});
});