If we look at interfaces in operating systems, we’ll see that there is usually a set of unified interface elements that’s shared not only by the operating system’s own tools, but also by third party programs running on that operating system.
For example, Apple’s OS X had a UI called “Aqua” for quite a few years now that gave the buttons and other interface elements a certain look a feel — a liquid look for the buttons and a more metallic/plastic look for the texture of the windows themselves. They’re now moving towards a more aluminum look that will bring it closer to the look and feel of their hardware products.
Until OS X Leopard, there were actually several ‘branches’ of the UI spread around Aqua. There were the plastic windows, the brushes metal windows and the darker aluminum windows. Buttons looked different in each one of these ’styles’. Leopard, the latest release of OS X, has unified the look across the board.
The interface in OS X looks the same on (almost) every app
