Why do app windows appear behind other app windows?

OK, I have an update I promised... Unfortunately, nothing seems to have changed.

The steps I took were as follows :

1) Manually shut down (Command-Q) all active applications.

2) Manually delete all the desktops in Mission Control, apart from the one I need to use (which can't be deleted anyway)

3) Delete the com.apple.spaces plist (and the associated lockfile)

4) Shutdown and rebooted.

5) After "Max" did it's 'thang' and rebooted, I verified that there was only one desktop in MC

6) Opened a Finder window (Command-N), and opened (double-clicked) a known good dmg file.

7) The installer window opened up behind the Finder window - again.

This is with one desktop only, and just Finder active. The same thing happens with any .dmg file - randomly, about once every 15 tries, the window opens normally - but I think that has more to do with the Z-order rolling over than anything else.

I've also tried this opening any .dmg (or any file that by default opens with the various Apple apps - Textpad, etc) in any Finder window, and the same darn thing happens!

I've also turned off the dashboard-as-a-separate-space option in Preferences, with no apparent change in behaviour.

I know this seems like such a little thing, but to a brand-spanking-new Mac owner, it's a major problem, because I don't know what to expect when I think I'm doing various things. Well, I know .dmg files are supposed to open in a window to allow me to drag the icon (or run the package, or whatever), but I don't see that happening, and it's driving me nuts, because I'm asking the Mac to do things, and I can't see it doing them! And since I'm a multi-desktop kinda guy, I naturally expect a bundled desktop manager to be able to be useable out-of-the-box, so to speak. It doesn't help one bit that there is absolutely no feedback of any kind when any of these processes takes some time. I'm used to disk activity indicators (I now have MenuMeters installed, so that's nice to have) or spinning cursors, but OS X doesn't seem to do that by default. At least, only a very few apps seem to trigger the cute little spinning wheel thingy, it sure doesn't happen when Finder does time-consuming things; so that makes me even more confused.

I ended up just going back to Finder, looking in my Downloads folder, finding the .dmg file, minimising all windows (which usually at least shows any install windows, but only in a single desktop situation), and manually opening the .dmg from within Finder, then minimising the Finder window, which usually shows up the install window. I've also learned that when the .dmg is opened, it appears in the left-hand side of Finder, so at least I can "find" (pardon the pun) the thing I'm hoping to install. So at least I'm learning stuff!

Now, whether this inappropriate and buggy window behaviour is an 'undocumented feature' of the Spaces application, I just don't know. Nor do I know if this is a legitimate issue with my installation of Lion. Unfortunately, I didn't get to see this happening before the Software Update process told me to install a bunch of OS updates a few minutes after I started using "Max", so I don't know if this is how the unit came configured, or if it's a problem with the 10.7.4 update, or a combination of the update and this unit, or what... I'm reluctant (but not totally averse) to performing a complete OS reinstall, if that's indicated, but from what I know, that's a fairly major undertaking, especially for a bug like the hiding windows thing!

So if anyone could help me figure out where this is going askew, I would very much appreciate the assistance!

And thanks to everyone who's helped out so far, I understand that this appears to be a 'corner case', and any time spent on this problem could be better spent elsewhere! It's a measure of my annoyance that I'm continuing to beg for help here, rather than raising the issue with an Apple specialist (which I understand may not fix the problem, according to some of the references posted here). So if we can fix this here, I'm sure it will be helpful not only to lil' ol' me, but anyone else with a similar problem (and they're out there, that's for sure!).

THanks again for reading all this... Cheers, Pete

Ah, I should have anticipated that... No, this happens simply by performing a single click (say, on a menu item) without accidentally bringing the application's main window back on top.

In the case of many install images (dmg files), the default Finder window is quite small; so with just a single Finder window visible on the desktop, if I try this (double-clicking on the dmg file in the Finder), I can see the dmg opening (just a transient window as the dmg is inspected/unpacked), and then in most cases the install window opens behind the Finder window.

I thought it might be a problem with clumsy fingers on the trackpad, so I installed a USB mouse, and was very careful not to move the mouse or otherwise trick the Finder window into thinking it was at the top of the Z-order, and it still happened.

It happened when opening the same dmg multiple times as a test; on 8 of 11 tests, the app install window opened behind the Finder, and 3 times it opened "normally" (i.e. in front of the Finder, as expected). This happens even with apps such as Xcode 4 (it took me quite a while to figure out what was happening, and I'd inadvertently reopened the installer 5 times!)

I hope this answers your question?

What a great find!

Unfortunately, there *is* no such plist in the Library/Preferences directory (or below). I seem to have everything _but_ the Spaces plist!

However, this is food for thought. Obviously there's a setting *somewhere*, I just have to find it.

Now, I do understand the difference between opening a window in a different Space (which actually seems to work remarkably well), and opening a window in the current space, but behind all visible windows...

However, the two aren't mutually exclusive - on more than one occasion, a window can be opened in another Space, that Space is switched to, but the window still appears beneath all the other windows (if any) in that Space. But it's far more common to see the issue in the current Space/desktop.

Oh, and it's not just Finder windows - most app install windows hide behind other windows, but I'm not sure if they're part of the Finder?

Either way, it seems Finder doesn't operate as reliably in the modern desktop (with or without a preferred Space) as most 3rd-party apps. And while restarting Finder usually 'fixes' the problem for a few minutes, sooner or later it returns.

Anyway, I'll look for the MIA Spaces/Desktops plist and see what I can find out.

Thanks again for your suggestions!

I just came back to let you know that I found another Preferences in my home directory... D'oh. You beat me to it, Martin!

I actually found it in terminal (I tend to trust text-mode low level tools much more than GUI tools), and then I figured out how to do the same thing from Lister's preferences. But thank you anyway Martin, I also appreciate learning about the Option-menu clicking and so on. I have much to learn!

OK, that makes more sense now. I'll work with what's there and see if I can characterise (or better yet, fix) the problem.

Thanks again for the responses.