This tweak allow you to toggle between the default 3D glass appearance or the 2D flat black appearance of the Mac OS X Dock.
Start a new Terminal session (in Finder click Applications > Utilities > Terminal).
To set this to 2D Flat, type (or copy and paste) the following command:
defaults write com.apple.dock no-glass -integer 1
To set this to 3D Glass, type (or copy and paste) the following command:
defaults write com.apple.dock no-glass -integer 0
To reset this setting to the default value, type (or copy and paste) the following command:
defaults delete com.apple.dock no-glass
To activate this tweak immediately, type the following command, or wait until the next reboot:
Close the Terminal session by typing
exit at the prompt.
Disclaimer: Making any changes to your system can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from these modifications can be resolved. Please follow the instructions carefully and use the information provided at your own risk.