When Notch first added glass to the game - in the version 0.0.19a, people told him it looked more like ice, so he quickly changed it in 0.0.19a_01 to the well known glass texture that has been in the game until the Jappa-fication. Up till today, we had only known this first glass texture as a few blue-ish pixels from far away, which changed with greenslimy finding a video on his old hard drive, featuring himself building a small house - in the version 0.0.19a. It's a good thing he built it with windows, since thanks to him, we now have a very good idea on how the glass looked. Here's the video in it's full Windows XP glory.