> nit can we do function open(panel, options) instead in case we want to add more params? same for display

That's exactly what I did initially but then caller `Panel.prototype.show` ended up calling it as:
`utils.show(view, model)` which was pretty ambiguous what `utils.show` depends on without looking into implementation. So I though this way it was more clear.

If you still think it's better to use `options` I don't feel very strongly about it.