Use classes instead of inline styles for hiding / showing

An example would be how the control bar used to be before using the state classes. By default it had 'display:none' defined in the CSS, and then show() was used to add display:block. That's the piece that wouldn't work anymore with this change. There's no internal examples of that anymore, and any external skins couldn't rely on that anymore since we're not calling show() anymore on anything, so I don't *think* we'll break people, but we might want to glance through the plugins and see if there's any use cases like this, where something's hidden by default.