I'm using multiple background images in a region, using following CSS attributes:

 -fx-background-image: url('ui/background.png'), url('ui/left.png'), url('ui/right.png') ;
 -fx-background-position: center, left, right ;
 -fx-background-repeat: repeat-x, no-repeat, no-repeat;

This works well, but, according to CSS3 :
"The first image in the list is the layer closest to the user, the next one is painted behind the first, and so on. [...]"
See : http://www.w3.org/TR/css3-background/#layering

The behavior in JavaFX is incorrect: the first background image appears to be the "lowest" one, but should be on top...