We need the ability to mark a Control as never receiving focus.

The focusTraversable property is nice, but not sufficient. That property won't prevent a control from receiving focus when clicked on.

There are at least 2 use cases when you don't want a control to receive focus:
 - when the control is in a toolbar
 - when the control (such as a combo box) is in a column header

For the first use case, http://bekwam.blogspot.co.nz/2014/11/javafx-cut-copy-and-paste-from-toolbar.html describes the difficulty trying to work around it.

For the second case, if you have a table where the items have many attributes you may want to allow the user to pick which attribute will be displayed in a column, leading to placing a combo box in the column header. When a user picks an item from the combo box, you don't want to steal focus from elsewhere.