Document selection = (Document)document.getRange(selectionStart, selectionLength);
try {
PlainTextSerializer serializer = new PlainTextSerializer();
StringWriter writer = new StringWriter();
serializer.writeObject(selection, writer);
selectedText = writer.toString();
} catch(SerializationException exception) {
throw new RuntimeException(exception);
} catch(IOException exception) {
throw new RuntimeException(exception);