If you change the block metadata (Holding shift and scrolling on your scroll wheel) and fast change the "currentslot" it changes the metadata of that block aswell...

Video: http://youtu.be/AjdlavqIUWw

Have a great day sir! (?) :D

I added some code to stop this behavior just one or two versions ago -- have you tried updating?

Uh..That's why i couldnt find the wrong thing about the code :)... No.. It's the Direwolf20 pack :P..