In addition to showing off holographic apps and revealing the name of its post-IE browser, Microsoft has also released its latest Windows 10 preview build for PCs today. The build (now called "Insider Preview" instead of "Technical Preview") introduces quite a lengthy list of new and experimental features, including Windows 7's Aero Glass design. Apparently, a lot of preview users asked Redmond to bring Aero Glass black, since company dropped the feature from Windows 8. To test it out, half of those installing the new build will see their Start menu and taskbar in normal transparency, while half will see theirs with a frosted glass effect.