Thank you. Thank you. Thank you.
Expose in Snow Leopard was driving me crazy since the first day it came out and I had given up hope of finding a solution. It's great to be able to get the old behaviour back even if it is a hack.
Here are a few things I'd like to add after doing a bit of further exploration myself.
First of all not the whole Dock.app needs to be replaced.
Inside Dock.app/Contents/Resources/ there are among other things a few executables and apps related to the Dashboard and Widgets. Here is a list of them:
DashboardClient.app
DockSyncClient.app
Widget Installer.app
widgetadvisory.app
dashboardadvisoryd
fetchadvisory
LoginDesktopPicture
I'd feel better to leave them untouched and the good news is that we can indeed only replace the actual Dock binary to get the old Expose back.
I have created a zip file containing just the required files which you can download from here:
DockHack.zip
But before continuing let's give credit where it is due since I took the liberty to combined files posted by others.
Thanks go to hamis92 for figuring this out in the first place, to miknos for this thread's guide and Dock skin and to Omena for the edited back buttons.
Now if you download the above zip file and extract it in your Downloads folder you can just copy the commands below to a terminal window to get the job done.
Note: Make a copy of the original Dock.app first, it is in /System/Library/CoreServices/Dock.app and you can just drag it to your desktop or anywhere else you like. It will be copied (not moved) since you only have read permissions. Keep it in case you want to restore the original files.
1. Replace the Dock binary and voila Expose in its true greatness!
Code:
sudo cp ~/Downloads/DockHack/Dock /System/Library/CoreServices/Dock.app/Contents/MacOS/
sudo cp ~/Downloads/DockHack/DockMenus.plist /System/Library/CoreServices/Dock.app/Contents/Resources/
killall Dock
Here is a screenshot of it, check the About This Mac dialog box:
With the 10A380 Dock you also get back the white menus and a bonus "Assign Application To" menu if Spaces is enabled.
See screenshot:
2. Apply Omena's fixed back buttons:
Code:
sudo cp ~/Downloads/DockHack/BackButton/* /System/Library/CoreServices/Dock.app/Contents/Resources/
killall Dock
See the two screenshots below to see what this fixes.
10A380 Dock:
10A380 Dock with Omena's edited back buttons:
3. Apply miknos's skin
This is of course optional but I personally really liked it and since we are already playing with the Dock's system files why not apply this as well.
Code:
sudo cp ~/Downloads/DockHack/Skin/* /System/Library/CoreServices/Dock.app/Contents/Resources/
killall Dock
Compare the screenshot below with one of the above to see the difference if you want to decide before applying it.
Finally I have been using the 10A380 dock on my iMac with 10.6.3 and had no issues at all. It seems quite stable to use it.