When you add an attendee that does not have any location information (no city, state, or country)
then a warning icon is displayed on the toolbar just above the time zone list.
For convince when you click on the icon the name of the person with no location information is
displayed in a context menu. If you click on the persons name the add-in will display the details
for that contact where you can update their information. Note however that if you update their
information, save it, and close the details dialog the add-in will not immediately recheck their
information and display a dialog box to select their time zone information from. If however you
add another attendee after update the prior attendee's address then the add-in will check the first
attendee's information and display a dialog box to select the time zone if it is not already defined
for their location.
