While running HelloDatePicker and changing the locale, these warnings appear:
4 27, 0027 6:02:09 ?? javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-text-background-color' while resolving lookups for '-fx-text-fill' from rule '*.list-cell' in stylesheet jar:file:/C:/sdk/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss
4 27, 0027 6:02:09 ?? javafx.scene.CssStyleHelper calculateValue
WARNING: Could not resolve '-fx-accent' while resolving lookups for '-fx-background-color' from rule '*.combo-box-popup>*.list-view>*.virtual-flow>*.clipped-container>*.sheet>*.list-cell:hover:filled:selected' in stylesheet jar:file:/C:/sdk/lib/ext/jfxrt.jar!/com/sun/javafx/scene/control/skin/modena/modena.bss

Steps to reproduce (very specific):
Start HelloDatePicker, click inside the Locale editbox.
Then click the combobox triangle and select any other locale (en-GB for example).
The warnings should display.