Early builds of the Mixed Reality Toolkit supported automatically configuring a project for HoloLens through a menu item. Unfortunately, that menu item didn’t explain which changes were being made to the project. Eduardo and Jared created added a visual window to explain each change and give developers the ability to opt out of each one. The window continued to evolve and remained in MRTK through all 2.x versions.

MRTK Text to Speech
The original MRTK Text to Speech system, which is still included in the toolkit today.