Bukkit

What steps will reproduce the problem?
1. Do /recipe
2. Click on any item that pops up in the crafting bench or product area repeatedly
3. Close Your inventory

What is the expected output? What do you see instead?
If you click on the item and close your inventory, it allows you to keep the item. I tried this in Survival mode and not OP. This allows people to duplicate and should be patched immediately. I suggest that you make it so you can't access your items and only a GUI of a crafting bench pops up, with the ability to drag or click on anything disabled.

What version of the product are you using?
V 1.1.3

Do you have an error log of what happened?
No, it did not cause any error.

Please provide any additional information below.

And is the block useable, or is it a ghost block?

The client and server can get out of sync when the server does non-vanilla behaviours (Such as denying a crafting recipe). There is no method in the Bukkit API to force a client to be resent their inventory. Clicking on the block in the inventory should remove the item. If this is not the case then please give the Bukkit version you are on.

It is a completely usable item. Both in Survival and in Creative. My Bukkit version is CraftBukkit V: 1.6.4-R2.0 the latest recommended Build for 1.6.4.

Whenever I tried this on my server I get a ghost item that vanishes upon reopening my inventory.