Error messages needed when entering overlapping/illogical times on Manifest Legs

Currently, when you try to enter an overlapping or illogical time on individual Manifest Leg date/time fields the only indication that you are trying to enter an incompatible time is when one of the other times becomes unchangeable. This can be a conflict with either the preceding or the following leg. It would be FAR more intuitive and useful to have an actual message of what's wrong instead of just a time that is stubbornly unchangable