Hey some AH actually removed the 5 stars I gave to this application. Apparently they don't like this app or they are displaying their total ignorance. Moronic behavior doesn't work on MacUpdate.

"Does anyone know of an app that lets you spread ONE window across at least TWO spaces?"

Maybe with CodeTek Virtual Desktop Pro (orphaned by the developer about five years ago). I'm not aware of any current product that does.

"I understand the use if you have multiple apps on each space"

Virtual desktop apps are generally less useful to me that way, e.g. who wants to run a VM app in the same space with other apps? :)

An exception is for multiple apps with windows small enough be displayed simultaneously (with minimal or no overlap) and interacted with in a single space.

"but most of the time you've got one window > one space, so it's just a "transition effect" for switching apps, ain't it? ;-)"

No necessarily. I keep more than one window open, for one or more apps, in multiple spaces.

Leaving windows open in different spaces can be easier to visualize and interact with across that spacial plane than "traditional" app/window hiding/switching on a single desktop/space. It's sort of like having a larger virtual monitor, minus the support for windows to cross space borders (that you asked about). Using spaces lets me retain predictable window views/layouts that can't be achieved with single-space window shuffling.

Thanks for those explanations! :-)
I've tried for a while, at least two spaces, hoping I would slowly find how to take advantage out of it, but it doesn't bring nothing to my workflow.
Like everything on earth, something is good for someone, something else for someone else, that's life. :-D

"… but it doesn't bring nothing to my workflow."

That would be something. :)

Maybe you'll find it useful in the future if your workflow changes. Thanks for the followup.

>useless eye-candy

Spaces save me time. Time is money. To each their own.

I agree fully with Cowicide. He is right on! This app saves me time and as he stated "time is money"

To avoid any confusion, I wasn't particularly talking about this app (the reason why I didn't make a proper "review" — no, I'm not the "AH that removed the 5 stars" ;-)), but about Spaces in general, though I wouldn't give bad names to people loving Spaces: "To each their own" as wrote Cowicide (being French, I didn't know how to say it in good English ;-))
My aim was to find an app to split windows across 2 spaces (specifically mixing a ProTools session with lots of tracks would be great, or putting the Mix window on a space and the Edit window on another one) but I still haven't found any.
I'll retry Spaces some day, I swear! ;-D

Aargl, I'm not sure I understand exactly what you want to do with your windows, but it sounds like Mavericks might give you more options. Should be getting released pretty soon, but of course, YMMV.

After about two more weeks I have had no problems. The hotkeys were easy to configure, vertical and horizontal window-drag to a different space, navigation and the grid view work well and I am very satisfied. I have a 4 x 4 grid (16 desktops) and use about 10 of those pretty regularly. This app brings back the pre-Mission Control interface - very nice, highly recommended.