Web Page Inspector

I wrote a small JavaFX Application to inspect Javascript within HTML pages. It loads and browses sites, shows the HTML source, shows an overview of the text of a page, provides a simple Javascript terminal, and runs Javscript files from disk. I’m thinking with some careful perusing it can be at least a little shorter and more succinct. How can this implementation be enhanced?

import java.io.File;

import java.io.IOException;

import java.nio.charset.Charset;

import java.nio.file.Files;

import java.nio.file.Paths;

import java.util.ArrayList;

import javafx.application.Application;

import javafx.beans.value.ChangeListener;

import javafx.beans.value.ObservableValue;

import javafx.concurrent.Worker;

import javafx.event.ActionEvent;

import javafx.scene.Scene;

import javafx.scene.control.Alert;

import javafx.scene.control.Alert.AlertType;

import javafx.scene.control.Menu;

import javafx.scene.control.MenuBar;

import javafx.scene.control.MenuItem;

import javafx.scene.control.MenuItemBuilder;

import javafx.scene.control.TextArea;

import javafx.scene.control.TextField;

import javafx.scene.input.KeyCode;

import javafx.scene.input.KeyCodeCombination;

import javafx.scene.input.KeyCombination;

import javafx.scene.input.KeyEvent;

import javafx.scene.layout.BorderPane;

import javafx.scene.layout.GridPane;

import javafx.scene.layout.Priority;

import javafx.scene.web.WebEngine;

import javafx.scene.web.WebView;

import javafx.stage.FileChooser;

import javafx.stage.Stage;

public class Browser extends Application {
    private static final String help = ""

        + "dir=function(x){"

        + "rv="""
Solution