Apple announced OS X 10.10 Yosemite earlier this month at WWDC with a whole new light and flat design. They also announced a new “Dark Mode” that’ll make the interface little bit darker. The setting was however not available in the first beta of OS X Yosemite, but you can enable it in the second beta with the following command:
sudo defaults write /Library/Preferences/.GlobalPreferences AppleInterfaceTheme Dark
Restart your Mac to see the difference. Attention, you can only enable this optie in the second beta of OS X Yosemite or higher! To revert to the original light interface use the following command:
sudo defaults write /Library/Preferences/.GlobalPreferences AppleInterfaceTheme Light
do you mean to have “delete” in the second defaults command?