Thanks for the bug report, the webbrowser module should be fixed in the next build.
@ClareMacrae I don't think this has anything to do with your issue – I have actually removed the 'sidebar' presentation style a couple of months ago, and I don't think it's coming back. Quite frankly, this isn't a feature that gets used a lot, and it's really difficult to make it work well with adaptive split-screen UI. Going forward, 'sidebar' will probably just behave like 'panel' instead of getting stuck (which is what happens right now, I think). I could also imagine implementing the kind of "docking" functionality for the accessory panel that I have in Pythonista 3, which is basically like a sidebar, but this probably won't happen in v. 1.3.