Microsoft Windows doesn’t allow use of 3rd party themes by default. Earlier, VistaGlazz allowed you to patch your Windows Vista system files to use custom styles and themes. Now, UxStyle Core is a new free app that allows you install the third-party themes easily without playing with system files. This software is still in beta and does not have theme manager, user interface and will run as a service in background allowing you to use 3rd party themes. The tool handles the enabling/disabling of custom theme support and the kernel driver handles patching.
UxStyle supports Windows XP, Windows Vista and Windows 7. It runs as a service in background, that we can see through task manager under the name Unsigned Themes, and it will allow you to use 3rd party themes.