The 'Always open folders in a new window' check box in my Finder Preferences doesn't seem to do anything. I would much prefer to just have ONE folder open at a time, but whether or not I 'tick' this box I always get multiple folders on top of each other. A quick 'apple w' gets rid of them so its no great problem, but I've worked on other iMacs where this doesn't happen.
I thought it may have worked because the first folder I opened (after 'trashing' that file) was viewed as 'icons'. As soon as I chose 'view as list', subsequent folders were on top of each other.
Strange issue, here if I choose to open folders in new I double click over any folder using Icon, Column, List or Cover View and folders open in a new Finder's Window, if I choose not to open folders in new window I double click and the same window is used to display contents in any View option.
More strange is that some days ago I made a presentation where folders were opening in new windows and should not, now I just made this test so I could post results here and settings were followed, different from this presentation day.