Yet another pointless UI change.

[maverator 6]

This time instead of changing it to make it uniform throughout, it's changed to make it...non-uniform because apparently the side bar needs to be a different color for some reason. How about either pick a theme and stick with it or better yet (gasp) allow users to customize it for themselves.

[weaverh 4]

You can change the color back. 

 

From their release notes: 

• The most obvious one is we’ve made the sidebar dark to better differentiate the sections.  If you’ve grown accustomed to the Yosemite style light sidebar you can keep it.  Just select the View : Sidebar Options menu and select Use Light Sidebar.  Let us know if you like the dark sidebar.