What's interesting about this setting is that it appears that in the future window borders may also change color as well, leaving behind the boring gray color. (windowscentral.com)
Much of what changed about the desktop from Windows 7 to Windows 8 could be seen in window borders, which lost their transparent glass look and became flat and opaque. (howtogeek.com)
In fact, Microsoft Edge, the new browser that comes with Windows 10, actually uses less chrome — the developer term for window borders and other interface elements — than Chrome. (pcmag.com)