Not at my Mac, so can't easily try this, but what happens if you type in your dates using a longer format? Say "22 June 2010" or "22/6/10"?
Also, do you know that you can specify dates such as "+1d" (tomorrow), "+2w" (2 weeks from today), etc.?
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omnifocus@omnigroup.com — forum posts aren't necessarily seen by the right people.