[abh19]

I agree, this behavior didn't seem intuitive when I first used it, but it works this way because there are two things to do in the calendar inspector: pick a date and set a time. It would certainly be annoying if the box closed after clicking on a date without letting you set the time.

You have three ways of closing the box: double-click on the date square you want to select, press escape, or click on the calendar icon.