CSSTUDIO-3429 Call pane.layout() on the JavaFX Application Thread at a later point in time.

Author: abrahamwolk

app/display/representation-javafx/src/main/java/org/csstudio/display/builder/representation/javafx/widgets/ByteMonitorRepresentation.java

@@ -83,6 +83,8 @@ protected Pane createJFXNode() throws Exception
         horizontal = model_widget.propHorizontal().getValue();
         addLEDs(pane);
         pane.setManaged(false);
+        Platform.runLater(() -> pane.layout());
+
         return pane;
     }