A few years back, Apple released the OS X update Yosemite for Mac, drastically changing the way that the user interface appears. The first thing you may have noticed with this transition is that the icons for various different apps changed, becoming less glossy and three dimensional, and adding distinguished color gradient effects.
If you are anything like me, it may bother you that certain third party software developers have neglected to update their app icons. For me, Avid's Sibelius is one of the only icons I keep on the dock that does not have this modern look. It sticks out like a sore thumb. It's hideous, actually. So naturally, I changed it.
DeviantArt has a bunch of Yosemite themed icon remakes available. Click here to download a much improved Sibelius icon, depicted below. They also have icon replacements for Pro Tools, Avid Media Composer, and tons of other apps. Following the link also includes very clear instructions on how to properly make the icon change on your computer.