I just did a page where an aggregate model summarized per day opened up a detail list with all job entries for that day. To accomplish this I needed to use the grouped datetime field (DAY_ONLY) and compare it with a DAY field on the detail records. However there seemed to be no way to get the DAY value to the condition. I created a aggregation for the day (MIN(DAY)) that was available on the row but it's not possible to use this alias name in the condition. By editing the XML and putting the alias name on the condition I got this to work. I think it would be a good idea to include the alias names in the popup for values in Activate & Set Value Conditions dialog.