It would be helpful if you could add keyboard shortcuts to use within the date picker. I think I've suggested this before, but can't find it, so trying again.
Two possible ways this could work (either or both would be nice).
- key shortcuts for date setting - this is used by several other programs I've come across. It works by assigning useful dates to particular keys, which only work this way when a date picker is activated. For example typing "t" enters "today's" date in the field. "m" gets you the first day of the current month ("h" gets you last day of the month), "w" gets you first day of current week ("k" gets you last day of current week), likewise for "y" and "r". CTRL+Left Arrow moves date back one, CTRL+Right Arrow moves the date forward one, "up-arrow" gives you previous month but same date otherwise, "down-arrow" the next month but same date etc. All very logical, and handy once you know it is there to be used. And probably not that hard to set up.
- smart guesses for date setting - this is also used by several other programs I've come across. Here, you enter something that the date picker then uses to guess what date you mean. So entering "today" gives you today's date. Tomorrow gives you tomorrow. '3' gives you 3rd of current month. 7/10 gives you 7 October in current year (if you are british) or 10 July (if not). Next Thursday gives... and so on. Probably harder to set up, but useful too.
The alternative is what we have currently: if you enter a malformed date in (say) a time entry dialog, the entry gets entered, but with a 'null' date. Really not very helpful...