workaround/fix for JavaFX FlowPane bug of not wrapping children.

Bug reported by Benjamin Peters (@dedeibel) see #163
N.B. in combination with StackPane (ie not managed), the FlowPane does
not automatically wrap the children. Forced the behaviour by explicitly
setting the width, height and preferred wrapping widht of the FlowPane.
Shape does not scale consistently (some Schmidt-trigger like behaviour
... intrinsic to JavaFX layout manager???)
At least it wraps now ... so we leave it at that.

chartfx-chart/src/main/java/de/gsi/chart/ui/ToolBarFlowPane.java

@@ -47,12 +47,10 @@ public ToolBarFlowPane(final Chart chart) {
         this.setMinHeight(0);
 
         this.setShape(ToolBarShapeHelper.getToolBarShape(this.getWidth(), this.getHeight(), cornerRadius.get()));
-        this.setPrefWidth(USE_PREF_SIZE);
 
         this.setAlignment(Pos.TOP_CENTER);
         this.setMinWidth(0);
         setPadding(calculateInsets()); // NOPMD
-        VBox.setVgrow(this, Priority.ALWAYS);
         HBox.setHgrow(this, Priority.NEVER);
 
         ChangeListener<Number> toolBarSizeListener = (ch, o, n) -> {
@@ -69,18 +67,20 @@ public ToolBarFlowPane(final Chart chart) {
     }
 
     private void adjustToolBarWidth() {
-        final double maxLength = 0.90 * chart.getCanvas().getWidth();
+        final double maxLength = 0.60 * chart.getWidth();
         double length = 0.0;
         for (Node node : this.getChildren()) {
             length += node.prefWidth(DEFAULT_TOOLBAR_HEIGHT);
         }
         length += 4 * cornerRadius.get();
         final double wrapLength = Math.min(maxLength, Math.max(length, 50));
+        this.setPrefWrapLength(wrapLength);
+        this.setMaxWidth(wrapLength);
+        this.setWidth(maxLength);
+        final int height = (int) Math.max(getHeight(), Math.max(getBoundsInParent().getHeight(), getBoundsInLocal().getHeight()));
+        this.setMinHeight(height);
 
-        this.prefWrapLengthProperty().set(wrapLength);
-        this.setMaxWidth(maxLength);
-        this.setWidth(length);
-        this.setShape(ToolBarShapeHelper.getToolBarShape(wrapLength, this.getHeight(), cornerRadius.get()));
+        this.setShape(ToolBarShapeHelper.getToolBarShape(wrapLength, height, cornerRadius.get()));
     }
 
     /**