Modifying the items of ChoiceBox, one get many css warnings on stderr (see an extract below).
Test case attached.
One don't get any warning with FX 2.2.x

May 30, 2013 6:36:50 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-color' while resolving lookups for '-fx-background-color' from rule '*.context-menu' in stylesheet jar:file:/C:/wksfx/sb20/scenebuilder-binaries/jdk1.8.0/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.css
May 30, 2013 6:36:50 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-color' while resolving lookups for '-fx-background-color' from rule '*.menu-up-arrow' in stylesheet jar:file:/C:/wksfx/sb20/scenebuilder-binaries/jdk1.8.0/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.css
May 30, 2013 6:36:50 PM javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-color' while resolving lookups for '-fx-background-color' from rule '*.menu-down-arrow' in stylesheet jar:file:/C:/wksfx/sb20/scenebuilder-binaries/jdk1.8.0/jre/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.css
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