In my one and only visit so far to JavaOne (sorry guys, you may have won the hockey, but between spotlight, dashboard (and its associated neat additions to WebKit), and all the other cool new stuff, Apple wins the bulk of my attention this week), I was given the five-minute demo of Project Looking Glass: Sun's 3d window manager which has just been open-sourced.

I don't claim to have made any in-depth analysis or testing. I do claim to be opinionated, prone to rash first impressions, and to have been using computers for long enough to have some idea of what works, and what doesn't.

Positive

• Nice eye-candy

  I'm an OS X user, so I can't really complain about eye-candy. A desktop environment that looks good is just more pleasant to use.

• Clear distinction between foreground app and background.

  The way the background apps actually move into the background is a good, informative effect. OS X accomplishes something similar (but more subtly) using drop-shadows.

• Nice effect for virtual desktops

  Virtual desktops are navigated between by spinning your perspective from side to side. This is a cool visual clue for where you're going that might reduce one of the main problems with virtual desktops by helping you maintain a spatial memory of where you left some windows.

• Interesting tilted window effect

  I'm not so sure on this one: it almost dropped down into the next section, but the way windows in the background can tilt slightly seems a quite effective way to increase screen real-estate. The visual cue of being angled backwards makes the shrinking of the content of the window much less disconcerting than if it had just been scaled.

• Doesn't try to do too much

  It doesn't attempt to have you fly around in arbitrary 3d space finding your windows. It could have, but that would have made it totally unuseable.

Neutral

• Side-on windows

  Windows can be minimised by flipping them side-on. The window title is written along the "spine", and you have a very small angled view of what's on the face of the window. I just don't see this as being very useful: the minimised windows still take up far too much space, and speaking personally, I don't see the point of minimising windows - they're just as useful hidden, or parked out the back of the desktop. (Exposé obviously helps me here)

• Boring-looking applications

  Surrounded by the cool new window manager, the regular X Window apps with their very X Window-ish widgets and window decorations look decidedly drab and out of place.

Negative

• Still clumsy

  The demonstrator (who had presumably been doing this for three days already) had some trouble manipulating windows that had been tilted in the background or flipped on their side. I wasn't given the chance to try this myself.

• Notes on backs of windows

  This is one of those features that looks cool in a demo, but actually reduces the usability of the environment in practice. I almost never want to associate a note with a specific window, and since the contents of windows change pretty often it's incredibly unlikely that the note will remain relevant for long.

  The existence of the notes, however, will make closing windows a questionable affair, because you'll have to be warned about possibly destroying stuff that's completely invisible to you when you hit the close button. I'd much rather a desktop-wide notepad that can fly in, dashboard-style.

• Crappy demo CD app

  The demo "cool 3d effects" app is a CD changer that spins a pile of CDs around. It looks cool, but compared to its two-dimensional alternatives, it's a huge step backwards in usability. User interfaces that try to model physical objects are almost never a good idea. We shouldn't be encouraging people to write awful interfaces like this by using them in demos.

  ...which begs the question: if that's the best they could come up with for the demo, is it really a good idea to try and follow that path in other applications?

All in all, Looking Glass looks like a good start. It introduces some interesting ideas to the desktop UI, but I don't think I'd want to use it seriously in its current form, even ahead of all the other dismal Linux UIs. Which is fair enough, it's an experiment and not meant for that kind of use yet.

One thing Apple consistently get right, is that eye-candy is best when it's applied to something that is already useful in its own right. Minimising a window is useful, minimising with a genie effect or by flipping the window on its side is kinda cool. Ditto with the way Dashboard widgets shimmer into view when you open them, or flip over to reveal their preferences. Even better is when the eye-candy enhances an already useful feature, such as the ways that the cube effect in OS X's fast-user switching, or the sweeping viewpoint in Looking Glass's desktop switching add a spatial element to the transition.

When looking cool comes before the feature that is being made to look cool, that's when problems start occurring.