One of Snow Leopard’s new features is Dock Expos
Lost in this new functionality, at least apparently, is the ability to view the OS X 10.5-style Dock contextual menus–those that offer options specific to the program. In 10.5, for example, if you click-and-hold on the Mail icon in the Dock, you can check for new messages or compose a new message using the contextual menu that appears.
As you may have discovered already, you can still get these menus to appear in 10.6–you just need to Control-click on the Dock icon, instead of using click-and-hold. (This also works in 10.5, of course.) Once you get used to using a Control-click, I think this structure provides a good solution–you get the old behavior with one action, and the new behavior with another.
However, if you really hate Dock Expos
defaults write com.apple.dock show-expose-menus -bool no killall Dock
With that, Dock Expos
defaults delete com.apple.dock show-expose-menus killall Dock
Thanks to
Mac OS X Hints contributor Swordfish> for sending this one in, and to Jeff Johnson of Lap Cat Software, who
discovered the hidden preference to disable Dock Expos