Greyed out "close", "minimize", and "zoom" controls with Yosemite
After updating to Yosemite, the "close", "minimize" and "zoom" controls for windows are not in color. They are shown in black and white, only. I am using a 13-inch mid 2010 Macbook Pro with 4 GB memory. Any ideas on what I need to do to get the colors back? I expect that there might be other areas in OS X where I have the same problem. I will appreciate any help you can offer. Thanks.
macbook pro, Mac OS X (10.6.2)