While running HelloDatePicker, with the focus on the DatePicker control, F4 can be used to open the DatePicker calendar. Alternatively, the Alt-Up/Down Arrows can be used for the same purpose. These arrow keys work fine when JAWS is not running. If JAWS is running, the Alt-Up/Down Arrow keys no longer work for that purpose, they (and also Alt Left/Right Arrow keys) will do nothing except occasionally cause HelloDatePicker to exit, and sometimes even force JAWS to abruptly exit.

To reproduce the problem on Windows 7/8:

While running HelloDatePicker along with JAWS screen reader, Tab to the DatePicker control. Press either Alt-UpArrow or Alt-DownArrow, the calendar will not open. At that point, continually press Alt-Arrow (any arrow) and you should see HelloDatePicker close down. If not, Tab around and back to DatePicker and try again. It is fairly easy to reproduce on my Win 7 Dell Laptop.

On Windows 8, JAWS does prevent the Alt-Up/DownArrows from opening the calendar, but does not shut down HelloDatePicker or JAWS in my experience so far.

From Spec (Date Picker):

F4: If the calendar does not open automatically, pressing F4 key opens/closes the calendar. Date that is displayed in the field is highlighted when the calendar is open.

ALT-UP/DOWN ARROW: If the calendar does not open automatically, pressing F4 key opens/closes the calendar. Date that is displayed in the field is highlighted when the calendar is open.
(There appears to be a cut/paste typo in the document, I believe F4 in this second case should be Alt-Up/DownArrow)...

See:

https://wiki.openjdk.java.net/display/OpenJFX/Keyboard+Navigation

under "Date Picker".

Upped the priority one tick due to the forced closings.

The HelloDatePicker Sample is run from Hello.jar as follows:

java -cp Hello.jar hello.HelloDatePicker