This only works if the "Look up" checkbox is checked in Trackpad settings.

Nice tip - I didn't know that one.

The only place it doesn't work - is in a dock folder. One still has to hover the cursor over the image/film/doc etc and use the space bar.

Ooh, nice tip! And I think this is one that isn't in my book! (Although I haven't actually got a copy at hand to check.)

This only works if you have the Look Up (tap with three fingers) setting turned On for your trackpad settings.

Hmm, not for me. It is checked, but it still does not work. Well, I was just curious and prefer the space bar anyway.

As to not working in a Dock folder, neither does 'Quick Look-Spacebar'.
The spacebar just opens the file in the relevant Application same as the return key, notice how a repeat spacebar does not close the file as it would in Quick Look.

'QUOTE' As to not working in a Dock folder, neither does 'Quick Look-Spacebar'.
The spacebar just opens the file in the relevant Application same as the return key, notice how a repeat spacebar does not close the file as it would in Quick Look.'QUOTE'

In Mountain Lion 10.8.4 you CAN hover the cursor over an item in a dock folder ( not click on it ) & then click the spacebar to Quicklook the item.

hover over a text file in the Documents Dock folder, now press the spacebar, notice how it opens in "Text Edit", this is not the same as 'Quick Look'.
hover over a pdf file and press the spacebar, guess what, it opens in 'Preview', again not a Quick Look view.

I dont know what the difference is between our systems jbarley, but -

if i hover the cursor over a pdf ( WITHOUT clicking the icon ) & hit the spacebar - it quicklooks it. Same with a text doc - same with a movie - same with an audio file.

If i CLICK on the icon - it opens it with the relevant app ( Preview/Textedit/Quicktime player/iTunes etc etc ).

My dock folders are set to Grid view .

This certainly didn't work in Snow Leopard but was brought in with Lion & continued with Mountain Lion. Ive been using it for the last couple of years.

It appears that the difference would be...
I'm using 'List' mode, I tried your 'Grid' mode and indeed QuickLook is available, unfortunately though not in List mode.

It is available in LIST view using this tweak. It still seems to work in Mountain Lion even though the hint is for Snow Leopard.

http://hints.macworld.com/article.php?story=20090903104925782.

It does however unfortunately mean that one cant drill down through the list view.

That tip, which was originally for OS X 10.6 does not work on my 10.8 system.
Terminal comes back with the error "command not found"

I just reversed it through Terminal adding NO rather than YES on my MBP and it removed the list view change.

I then added the command from that tip in Terminal & it worked fine. ( Running 10.8.4 )

Not sure why its giving you that message.

Your commands worked.
My mistake when using the link you posted was in copy-pasting the total line, including the $ sign.
Duh!

The commands are :

defaults write com.apple.dock use-new-list-stack -bool YES

killall Dock