ModernUI Tuner.
ModernUI Tuner is my latest tweaker which allows you to change several hidden but very useful options of the fresh Windows 8.1 Feature Pack/Spring Update 1.
This app has been superseded by Winaero Tweaker and is no longer being maintained. Use the following options from Winaero Tweaker:
You can download Winaero Tweaker here: Download Winaero Tweaker.