Microsoft's Windows 10 preview build 10158 for PCs adds Edge browser branding and other tweaks, just a month ahead of the start of the operating system's rollout. By Mary Jo Foley for All About Microsoft | June 30, 2015 -- 11:40 GMT (04:40 PDT) With exactly one month to go before it begins rolling out Windows 10 for PCs, Microsoft made available to its Insider testers another preview build of the coming operating system. Windows 10 Build 10158, which went to Fast Ring testers on June 29, now includes the "Edge" branding for the browser that was formerly known as "Project Spartan." The newest official preview build of Windows 10 Mobile for Windows Phones last week also now has the Edge browser branding. With the change in branding from Spartan to Edge, Microsoft has introduced a new app ID that causes any favorites, cookies, history and Reading list items saved in Spartan to be lost, so testers who want to save these need to back up their favorites, as Microsoft officials warned a week ago.The Edge app in the new Windows 10 test build includes new customizations, a dark theme, password and form-fill options and other tweaks. The 10158 build includes general UX improvements and bug fixes. There are several updates specifically for Continuum, Microsoft's feature to smooth transitions between Tablet mode and Desktop mode. The Photos app has been updated, as has the Snipping Tool. The build includes fixes for Windows 10 preview specifically for Surface 3 and Surface Pro 3. Also, as Microsoft execs said would be the case, the Insider Hub is no longer pre-installed with this build, but users can add it back. Today, June 30, Microsoft will be releasing a test build of the Windows 10 software development kit to Insiders, as officials said would happen. This SDK will include an emulator for Windows 10 Mobile. A couple of updates to Cortana, Microsoft's personal digital assistant, in the new test build. Cortana is integrated with Office 365 as of this build. That means testers who are in the First Release program for Office 365 will start seeing new Cortana capabilities connected to their work activities (such as where to go for the day's first meeting and how long travel to that meeting will take.) Microsoft will begin rolling out Windows 10 for PCs and tablets on July 29. According to the company's TechNet site, Microsoft also will make available a time-limited evaluation version of Windows 10 Enterprise available on July 29. I've asked company officials if this means the full version of Windows 10 Enterprise -- and not just Home and Professional -- will be available starting July 29, but have not heard back.