I have discovered what I believe to be a mistake at many places
in login.css as part of FXML-LoginDemo.
     If you open the project in NB 7.3 and then open login.css,
there is lots of warnings on lines containing rgb(). First I thought
it was a bug in NB but it is not - we check rgb() according to
http://docs.oracle.com/javafx/2/api/javafx/scene/doc-files/cssref.html
where it is specified as

#<digit><digit><digit>
| #<digit><digit><digit><digit><digit><digit>
| rgb( <integer> , <integer> , <integer> )
| rgb( <integer> %, <integer>% , <integer>% )
| rgba( <integer> , <integer> , <integer> , <number> )
| rgba( <integer>% , <integer>% , <integer> %, <number> )

but in FXML-LoginDemo there is lots of places where the following is found:

rgb( <integer> , <integer> , <integer> , <number> )

Surprisingly it does not cause any runtime problems but apparently
(according to the spec) it was meant to be

rgba( <integer> , <integer> , <integer> , <number> )

Changing rgb to rgba in these cases removes the warnings and a very slight
visible change in coloring can be seen when the demo launches.

--------------

I would recommend to check also css files in other samples for similar occurrences.