Thanks Naomi. I did find the thread you mentioned and have looked at John Koziol's textbox class. The surprising thing is that there doesn't appear to be a clean, easy way to edit datetime fields--they are fraught with pitfalls and minefields. I guess if I'm going to have to build my own classes, I might as well give them what they want--as opposed to what's easy as I'd hoped to do.

It looks like it will require 3 separate controls to edit the 2 datetime fields--that's still better than the 7 controls they have now. A textbox with a drop-down calendar control might help prevent the date validation issues. I'd like to use spinners for the times but restrict the hour portion to the business day and have the minute portion increment in 15-minute intervals. It would be elegant, but quite a bit of work. The more I mess with it, the more I realize that parsing and building the value to update the datetime fields is truly the easy part!