If you set Firefox as your default browser app, it will probably open the WebViews in Firefox instead. It's still going to show the history. You are essentially clicking on links and viewing them in a browser, it's no different than you navigating to the pages yourself. Jerboa itself does not have a browser, so it is not possible to view things "in" the app. At most, you get an embedded WebView that only looks like it's in the app.