/** Asks the user to choose a plain file.
    *
    * @param title What to put in the file chooser dialog title bar.
    * @return The chosen file.
    */
def choosePlainFile(title: String = ""): Option[File] = {  
    val chooser = new FileChooser(new File("."))
    chooser.title = title
    val result = chooser.showOpenDialog(null)
    if (result == FileChooser.Result.Approve) {
      Some(chooser.selectedFile)
    } else None
  }

  /** Asks the user to choose a directory, then returns (as an option)
    * an array of the files in that directory.
    * 
    * @param title What to put in the file chooser dialog title bar.
    * @return The files in the chosen directory.
    */
  def getDirectoryListing(title: String = ""): Option[Array[File]] = {
    val chooser = new FileChooser(null)
    chooser.fileSelectionMode = FileChooser.SelectionMode.DirectoriesOnly
    chooser.title = title
    val result = chooser.showOpenDialog(null)
    if (result == FileChooser.Result.Approve) {
      Some(chooser.selectedFile.listFiles())
    } else None
  }

  /** Returns the words from a given text, where a word is defined
    * as a nonempty sequence of letters only.
    *
    * @param text The input text.
    * @return A list of words from the text.
    */
  def getWordsFromText(text: String): List[String] = {
    ("""[a-zA-Z]+""".r findAllIn text) toList
  }}