Windows Server 2012 R2 Datacenter / Launcher 1.3.9 / Java 1.7.0u45 64-bit
Steps to represent this bug:
1. /gamemode 3
2. take a creeper/spider/enderman's camera, and the shader is turned on
3. press ESC and then change the language in the menu
4. back to game and you will find the shader stopped working
Here is a video: http://youtu.be/_phGNmoJeKI
p.s. I didn't click the Super Secret button in this video.