With some web apps, you can actually lose data because it's so easy to inadvertently swipe back in Safari for Lion. This only seems to happen when the page tries to catch the unload event and throws up a "Leave or Stay" dialog. Choosing the latter does _not_ return the user to the previous page as it should, so if you were in the middle of typing something when you accidentally triggered the Back event, you've lost that work.<p>I've seen this happen with JIRA and Gmail. Hacker News, which does not attempt to catch a user with unsubmitted data, works just fine. You can type a comment, swipe back, then swipe forward, and your comment will still be there.