I'd be willing to bet that most people don't encounter horizontal scrolling on a regular basis. At least I sure hope not; it's hella annoying. The only cases where I can think of it coming up (for a full page, at least) is when there is an over-sized image or on the occasional artsy site where it's designed that way intentionally. Perhaps horizontal scrolling comes up more often for people using small screens--on a netbook or phone or something--but even then I imagine it's fairly rare.
The use case? Inline comments, feedback boxes, contact info, control panels, really anything you want to have immediately available but out of the way most of the time. Is this the best way to implement those? Not always, of course, but probably enough to warrant its existence.
Oh I hate horizontal scrolling, but it seems odd that the contents of the page are shifted to the left in the demo without any clear way to shift back. Maybe I missed something, but that's usually an indication of a poor UI paradigm. And I'm not arguing it shouldn't exist, just commenting that it's usefulness isn't immediately obvious. More choices are always good though!
Ah, that's what you meant. You just have to click on the original page to shift it back. It was intuitive to me, but I can definitely see people not realizing it. You're right, they should definitely indicate how to get back in some way.
It's really quite an awesome way to show more content. A lightbox works too, but is not well suited for content with more vertical length then width.
IMO, it's unacceptable for a user to have to scroll horizontally in the first place. In fact, it's probably one of the most important usability constraints.
Pretty slick looking, will still need some development to make use more intuitive. Like there's no clear sign that I just click back in the main area to return to focus.
Ah, but in this implementation, clicking on the new content doesn't make it go away. It's really not intuitive for a first time user (like me for instance).
We actually used this effect inside of Twiddla for a while, with universally bad user response. Ditched it in favor of boring lightbox-style pseudo popups.
I just tried out Twiddla, it's really cool, congrats.
As per this slide-in UI, I'm going to change my mind here and say you're right. It really is kind of pointless... it's the same thing as a lightbox, only vertical, and more disruptive and disorienting.
I do think there could be some use for it... maybe someone will make a twitter app that uses it.. twitslide perhaps.. and we can all be amazed that they did it in x hours just as a side project.
For the record, that was 1998, not 1996, so I was off by a couple years in my earlier remark. I've taken the liberty of updating it so that it works in FireFox and Chrome now. (Sadly, sacrificing the document.all and document.Layers action that made it so great!)
For what it's worth, it never occurred to me that this was supposed to be an innovative new UI metaphor. I just assumed that the author was proud of himself for discovering element.scrollTo().
As noted above, it's not a good UI, nor is it revolutionary or even new. So I guess I have to argue that it is not, in fact, progress.
