On June 2 at WWDC 2014, Apple officially launched a new edition of the operating system for Mac computers OS X Yosemite with many new features and a new design. In a new promo video “The New Look of OS X Yosemite”, Apple focuses on the user interface of the operating system.
In addition to new effects in the OS, icons in standard applications, icons in the menu bar, buttons and other interface elements are updated . New video from Apple, dedicated to OS X Yosemite interface has been made available
Video about the design of OS X Yosemite from Apple: