Assume date fields

When entering data for a report, if we leave both date fields blank the report selects all records. Could we please further that expectation, and have the start field, if blank, assume the earliest date recorded, and the end date, if blank, assume the last date recorded.

Currently, if a date is entered for the start date and the end date is left blank, then all records are returned, both dated before and after the start date. I have not tested what happens if a end date is entered and the start date is left blank.