Regression: many css warnings with ChoiceBox

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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