In b42 getUserAgentStylesheet method is not always called.

CalendarPickerX in the JFXrtas project provides a custom stylesheet by overriding getUserAgentStylesheet. If the control is used stand alone in a Scene (CalendarTextFieldXTest1 class) then getUserAgentStylesheet is not called, thus resulting in an error:
SEVERE: javafx.scene.control.Control impl_processCSS The -fx-skin property has not been defined in CSS for CalendarPickerX@a8c488[styleClass=root calendarpickerx]

However, CalendarTextFieldX uses CalendarPickerX in a popup window. In that situation (CalendarPickerXTest1 class) the getUserAgentStylesheet method of CalendarPickerX is called.

To add to the confusion, another control (SpinnerX) also overrides getUserAgentStylesheet but it works fine.