Squib of the day: Live previews in alt-tab

True to my promise, here’s the first bug/squib of the day.

In GNOME bug 567757 someone is asking for live previews in the alt-tab window.  I can’t think why this would actually be useful, as opposed to pretty, and it sounds like a lot of work and a source of new bugs.  I am therefore minded to say no.  Can anyone think of why it might be worth the trouble?

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Thomas Thurman

Mostly themes, triaging, and patch review.

29 thoughts on “Squib of the day: Live previews in alt-tab”

  1. Might be handy to see how far a compile has gotten without having to raise the window, or to see the progress of a download, or to check if someone’s said anything in a chat window… etc.

  2. But does anyone really hold down alt-tab long enough for it to make a difference between what the state of a window was when they pressed it and what the state is now?

  3. I do hold alt+tab long enough to make sure I chose the correct window. Window titles are often meaningless so it takes a while if a lot of windows share the same icon. While I think this could be useful, I’m sure a proper clone of expose would be twice as useful (tested using compiz but I can’t run compiz all the time).

  4. I agree with that Patrys said, plus the alt-tab window is too small to be able to see much anyway

  5. Shiny lights are enough to convince many people that one thing is better than another?

    Also, yeah, I use compiz and regularly go into expose mode (i think technically called “switch mode” or something in compiz) to check the status of things.

    Although, I think (and I said it on the compiz forums) that the proper way for alt-tab to work is to just enter into exposE but with alt-tab functionality. Because, frankly, the bigger the window that you’re looking at the easier it is to see what you’re switching to, and what your options are. Pretty much the only reason i am ever willing to take my hands that far away from the keyboard is because everything is so much bigger.

    So yeah, focus on exposE, not alt-tab :)

  6. It seems to me this is what the Mozilla folks would call a ‘polish’ bug: if you’re going to show the window content, you might as well show what it looks like right now, rather than however long ago the window snapshots were taken.

    I’d suggest leaving the bug open as bait for other reporters to find (and for triagers to dupe against) and for volunteers to attach potential patches to, but leave it at lowest priority and with a comment saying that the feature won’t be added by the official Metacity maintainers.

  7. I think Screwtape is right. Its not a question of usefulness as much as thats just what a user naturally expects.

    I also agree that its best not to “waste” your time on it if there’s other work to be done. While its nice polish, I’m sure anyone who’s dying to have it already uses compiz anyway.

  8. “Can anyone think of why it might be worth the trouble?”
    Could a possible use case be:
    Two Inkscape documents open. One is a drawing of a cat, the other is a mockup of a website. Better to see the drawings instead of two identical inkscape logos. (or, the little black thing that used to be in the topleft corner)?

    We use previews for images and pdf’s in nautilus instead of just plain document icons.
    It would probably make less sense for, say, emacs or nautilus windows though.

  9. @Andreas: I think you miss the point a little; we already do show previews. The question is whether the previews should continue to update for as long as the alt-tab window is displayed.

  10. @John Stowers: It’s only enabled when the compositor’s turned on. (Maybe it should exist when compositing is off, too, but that’d be a separate bug.)

  11. KWin has such a feature since 4.0, called boxswitch effect. Since 4.2 it will be enabled by default for each user as it is the default alt+tab effect and compositing is enabled by default.

    Previews have quite some advantages. E.g. you have several windows from the same app opened. If you want to switch to one of those it is much easier to recognize the correct one when you see a preview instead only text. The boxswitch effect helps even more for that task as the windows are made transparent and the selected one is elevated.

    Personally I use the so-called coverswitch effect (inspired by iTunes coverflow) for alt+tab. It shows bigger previews of the windows, especially of the active one and those directly reachable via alt+tab or alt+shift+tab. This effect really changed my workflow. Especially when I am working with two windows I do not have to switch to the app any more if I just want to take a look at it. It is enough to use alt+tab to have a peak at it and to return to the previous selected app.

  12. ah I see you already have previews. So you can forget my previous comment as that was more about why previews are nice. Having live previews is not a difference in that case.

  13. Live alt-tab and exposé are normal effects that all the other OS do. If you want to compete with Vista or OSX you must give this kind of effect, face it.

  14. Inclined to agree with those voting against its inclusion– can’t see many use cases for such a feature in a transient view of your windows that only lasts as long as you’re holding down a key. Static thumbnail + mini-app-icon + window title seems plenty good enough for the vast majority of uses.

    FWIW, note that (contrary to other comments) OS X does *not* show live previews in its Cmd-Tab view– it doesn’t even show a static thumbnail, just the application icon. Live previews are shown in the Exposé view, but that’s a different kettle of fish.

  15. @Simone Malacarne
    Actually OS X doesn’t do thumbnail-alt-tab. But a big icon (128×128). Probably because it’s much faster for human minds to recognize the email icon(it’s in the dock/panel too!) rather than a thumbnail of, say evolution.

    For the rest, as you guessed, I actually think that thumbnailing a window is very a bad idea.

    Think of an icon as a graphical identifactor. Thumbnailing actually breaks this pretty bad.

    Second, there is no benefit. Thumbnailing (128×128) a window (conservative say 1024×768) shows 2% of the pixels (or 2% of the original information). Think about doing this on a normal laptop (1400×900) it’s less than 1 percent!

    For the live preview/’thumbnail’ we have exposè, here it makes sense since it we window size is as big as possible, instead of 128×128.

    Pretty please with sugar on top, Kill this thumnbnail ‘feature’, it’s eyecandy that doesn’t help – use expose for live previews/thumbnails. And plain icons for ALT+TAB. I know it sucks when having two inkscapes open, but then use expose or show the titles of all windows below the icon. (Inkscape could should the title,path or name of drawing for distinguishing serveral icons).

  16. Oops, posted as anon before. Thought openid would handle name/email :(.

    Yeah, I know how it looks :) (using metacity+compositor, thanks!!!).

    I still think that doing preview in expose is a better solution. It might be possible to come up with preview+icon solution that works great, I haven’t tried ;).

    The problem, is that preview only helps in cases where the same icon is shown twice (2xInkscape), but it in all other cases it’s significantly worse. It solves one issue but it’s much worse for the general case.

    But it is pure speculation – I have no data to back it up.

    One small issue with the current solution. Icons are aligned horizontally, so it’s harder to ‘scan’ with the eyes.

  17. @Thomas Thurman: oh, sorry, misunderstood that (and maybe I should fix my alt+tab keys) :)
    Yeah, that other thing sounds rather useless. Why would anyone want to have that?

  18. Wow, I am always amazed when this bug continues to pop back up. Anyone thought of having alt+tab just display icons, but staying on a selection for a fraction of a second generates a screenshot or live preview of the window selected? This should make quick alt+tabbing possible. We don’t waste time and cpu creating pixmaps for windows we don’t care about. We get a visual identifier when we have multiple windows and we aren’t sure which ones we want. Any takers?

  19. I think Jon Nettletons idea is a really nice solution. I mainly use OS X and really like seeing only the icons in Cmd-Tab, but having a preview appear after a delay would help in Metacitys case because of Gnomes and OS X’s different application vs. document paradigms.

  20. As much as I like the gee-whiz factor with Alt-Tab thumbnailing, I’ve found it distracting. I don’t know if this is a personal bias, a case of being set in my ways, or a true reflection of usability factors.

    I’ve used composited Metacity for around six months now, after using the “old” Metacity (and various versions of Windows and OS X) for years before. While the thumbnails have occasionally helped to distinguish between multiple windows of the same app, more often they’ve made it difficult for me to switch between apps.

    I agree with Frej-as-anonymous’s comments about the usage of that small space: an icon has been optimized for that small space, whereas a thumbnail is representing a small percentage of the useful content that makes it possible to distinguish. When shown thumbnails of a sparse white Web page and a text document open in gEdit, I still have to rely on the icons to decide which app to select – but now, the icon is secondary and harder to find visually than in a purely icon-only list.

    I think that thumbnailing (live or not) is better relegated to an Exposé-style switcher, and that Alt-Tab should revert to icons. Or perhaps a GConf option for Alt-Tab thumbnailing – yes, I understand the can of worms that suggestion opens. :-)

  21. I agree with John (previous comment), I find that thumbnails tend to distract me with composite metacity. I kinda liked the simplicity of just having icons.

    What I am suggesting is this: keep the thumbnails, but make the icons much bigger on top of them. Maybe have half of the overlaying space be used by the icon.

    Also, more importantly, please scale the text according to the screen width to make it big and easy to read.

  22. Preview in alt-tab is just great: Thanks.

    Is there any plan to add preview in desktop switching? This could be usefull too.

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