Fix custom fold CSS not being applied (#1000)

Author: Jugen

richtextfx/src/main/java/org/fxmisc/richtext/LineNumberFactory.java

@@ -17,6 +17,7 @@
 import javafx.scene.paint.Paint;
 import javafx.scene.text.Font;
 import javafx.scene.text.FontPosture;
+import javafx.scene.text.FontWeight;
 
 import org.reactfx.collection.LiveList;
 import org.reactfx.value.Val;
@@ -29,10 +30,9 @@ public class LineNumberFactory<PS> implements IntFunction<Node> {
 
     private static final Insets DEFAULT_INSETS = new Insets(0.0, 5.0, 0.0, 5.0);
     private static final Paint DEFAULT_TEXT_FILL = Color.web("#666");
-    private static final Font DEFAULT_FONT =
-            Font.font("monospace", FontPosture.ITALIC, 13);
-    private static final Background DEFAULT_BACKGROUND =
-            new Background(new BackgroundFill(Color.web("#ddd"), null, null));
+    private static final Font DEFAULT_FONT = Font.font("monospace", FontPosture.ITALIC, 13);
+    private static final Font DEFAULT_FOLD_FONT = Font.font("monospace", FontWeight.BOLD, 13);
+    private static final Background DEFAULT_BACKGROUND = new Background(new BackgroundFill(Color.web("#ddd"), null, null));
 
     public static IntFunction<Node> get(GenericStyledArea<?, ?, ?> area) {
         return get(area, digits -> "%1$" + digits + "s");
@@ -113,7 +113,8 @@ public Node apply(int idx) {
         if ( isFoldedCheck != null )
         {
             Label foldIndicator = new Label( " " );
-            foldIndicator.setTextFill( DEFAULT_TEXT_FILL ); // Prevents CSS errors
+            foldIndicator.setTextFill( Color.BLUE ); // Prevents CSS errors
+            foldIndicator.setFont( DEFAULT_FOLD_FONT );
 
             lineNo.setContentDisplay( ContentDisplay.RIGHT );
             lineNo.setGraphic( foldIndicator );

richtextfx/src/main/resources/org/fxmisc/richtext/styled-text-area.css

@@ -17,9 +17,3 @@
 
 /* For folding/hiding paragraphs. It's applied to TextFlow. */
 .collapse { visibility: collapse; }
-
-/* For LineNumberFactory, it's applied to Label. */
-.fold-indicator {
-    -fx-font-weight: bold;
-    -fx-text-fill: blue;
-}