For the first time in Technical Preview builds, with the Windows 10 build 9926, Microsoft has offered the start menu based on XAML, this isn’t liked by most Windows Insiders as they can’t resize it after unpinning tiles. If you don’t like the Start Menu offered in this build and want the Start Menu that appeared in the build 9879, you can get it with a registry trick, here is how.
UPDATE: This method of enabling 9879 build start menu no longer working in the build 10041.
Get Windows 10 Build 9879 Start Menu in build 9926
1. Open the registry editor by typing regedit in the run command
2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced, and create a new DWORD value with name ‘EnableXamlStartMenu’ and give it value as ‘0’.
3. Open the Task Manager, select ‘Windows Explorer’ in the Processes tab and click ‘Restart’, start menu of build 9879 will appear, check the screenshot below.
To get the Start Menu offered in this build, delete the ‘EnableXamlStartMenu’ key we’ve created before, restart Explorer or system.
H/T to @bavo