I do have a MDateEntryField in my GUI and it uses the Calendar popup.  I know that it is supposed to close as soon as it loses the focus, but that doesn't work if you pressed any buttons in the popup.  Then the popup will remain visible even if I clicked any other buttons in my panel.  So the user has to click the arrow-down button again in the DateEntryField to get rid of the popup which pretty much sucks.

Cheers,
ArKay