Metis is the first Open Source Runescape client available! It is written completely in Java, and has all the features you are looking for in a Runescape client, plus a few more features, such as it being the only stand-alone Runescape linux client!
Being dependent on Mozilla 5 libs isn't a wise approach. and Swing not using native components is slow, doesn't blend well, and bulkey. I would have used SWT for the graphical components, and SWT-webkit for the web stuff to reduce dependencies, and increase performance, and functionality. I saw the bulkey interface, get the "set mozzilla_five_home" message, and deleted it.