Would be useful if we could provide some kind of hint or setting that puts a Menu on the far right side of the menu bar. Sometimes apps will want to put menus of secondary importance (like "Help") in this position, but there is currently no way of doing this in JavaFX.

This idea was also mentioned very briefly at the end of the description for this feature request:

https://javafx-jira.kenai.com/browse/RT-14244