Using HelloPopupMenu, when the focus is on a collapsed submenu entry, Space Bar will expand the submenu list, but does not select the first item in the submenu list.

If the Space Bar is pressed again, the submenu list is collapsed and an NPE is thrown. This occurs on Windows and Mac.

Upped the priority one tick due to NPE.

From Spec (Popup Menu):

SPACEBAR/ENTER: Commit the value if the item is enabled. If the selected item is a submenu item, open the submenu and select the first item in the submenu.

See:

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

under "Popup Menu".

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

java -cp Hello.jar hello.HelloPopupMenu