As of the 1.7 update i can't get / set the blocks like piston head, repeater top etc that aren't getable without cheats in vanilla, and now they won't show up! The id is recognized but the slots in invs where the items are supposed to be are empty, other regular items do work? Anyone has a solution for this?
So if i run 1.6 Server but let 1.7 people join, it will work? Thats silly! They were perfect as place holders etc!
Mojang removed the ability to hold certain items in your inventory. It will actually cause the client to disconnect if you hack around that removal and tell the client it's holding one of those items.
Because they weren't actually items and Mojang doesn't make decisions based on anything but the vanilla game?
I suspect the Mojang coder who made the change could best answer that. My guess is it's partly to eliminate inventory duplication (eg. having 5 of the block-form of redstone dust and 5 of the proper redstone dust not being able to combine though they both place the same block), and the rest to eliminate any potential issues that could arise from placing the partial blocks (like half a bed block, the piston-movement block, etc)