Attached is a NetBeans 7.2 project that runs an app made of a single asset, a TextArea, containing "hello world".

If you triple click "hello" or "world" what you get selected is "hello worl": the trailing 'd' is not selected.

Don't be confused by the space: if you edit the FXML file to set the text to "helloworld" and take a triple click still the trailing 'd' is not selected.