Summary:On the first day of its Build developers' conference, Microsoft has released a new preview of Windows 10, the third new version in 30 days. Here's what's inside. By Ed Bott for The Ed Bott Report | April 29, 2015 -- 22:23 GMT (15:23 PDT) When Microsoft said they were picking up the pace of Windows 10 preview releases, they weren't kidding. Today, the company released build 10074 to both the Fast and Slow rings of its Windows Insider program. The latest update comes only a week after the last release and 30 days after the previous release. One subtle change in build 10074 is a change in the description watermarked on the Windows desktop. Instead of being labeled a Technical Preview, the new build is now an Insider Preview. That's no doubt a reflection of the rapidly approaching release date, which is now roughly 90 days away. This release marks the surprising return of Aero Glass, the transparent effect behind some user interface elements that debuted in Windows Vista, was refined in Windows 7, and disappeared with the launch of the flat Windows 8 user interface. In this build, Microsoft is conducting an A-B test, with half of Windows 10 installations getting the transparency effect behind the Start menu and taskbar and the other half getting a blur, "frosted glass" effect. The new build fixes one embarrassing bug from last week's release. You can now launch Windows desktop apps from the Start menu, instead of having to first pin the app to the taskbar. The blog post introducing today's release contains a laundry list of other improvements, including visual changes that join the Start menu and Cortana, additional Cortana capabilities (you can now ask for weather information and stock quotes, for example), improvements in the behavior of task-switching shortcuts, and improvements in the Continuum feature on hybrid touch-enabled devices. Anyone with Windows 10 installed will get the new build delivered via Windows Update. It is also available as an ISO for clean installs and for use in virtual machines.