Helper class to create a custom editor for a type T. The example "how to do" will be found for the Font Editor in the class Editors#createFontEditor(org.controlsfx.control.PropertySheet.Item).
See also {@link DefaultPropertyEditorFactory how to integrate a custom type editor in the PropertySheet.

public static final PropertyEditor<?> createFontEditor( Item property ) {
       return new AbstractPropertyEditor<Font, AbstractObjectField<Font>>(property, new AbstractObjectField<Font>() {
                   {@literal @}Override protected Class<Font> getType() {
                       return Font.class;
                   }

                   {@literal @}Override protected String objectToString(Font font) {
                       return font == null? "": String.format("%s, %.1f", font.getName(), font.getSize()); //$NON-NLS-1$ //$NON-NLS-2$
                   }

                   {@literal @}Override protected Font edit(Font font) {
                       FontSelectorDialog dlg = new FontSelectorDialog(font);
                       Optional<Font> optionalFont = dlg.showAndWait();
                       return optionalFont.orElse(null);
                   }
               }) {

           {@literal @}Override protected ObservableValue<Font> getObservableValue() {
               return getEditor().getObjectProperty();
           }

           {@literal @}Override public void setValue(Font value) {
               getEditor().getObjectProperty().set(value);
           }
       };
   }