make links in Info pane clickable

exposes one bug I haven't tracked down yet: the Info dialog disappears if the app loses focus, because it's set as a Tool window.  No problem there, but the Info button tries to toggle its state, and it reports isVisible() as true even after it disappears, so you have to hit Info twice after it disappears to get it back.  Pretty easy to trigger now that links take you to an external browser...