Woohoo! We've updated the autocomplete tools to include a lot more information, and hopefully generally work better. The old tool was a custom implementation from back before ACE included an autocomplete. We've finally ripped that out and replaced it with the ACE built in auto completer. You'll notice that you get a lot more information, and the keys and buttons work more like you'd expect.
You'll also get some context for what various methods and properties are for. This help text should get better over time as we expand the library of information.