Can't move blocks in GUI screens using mouse or shift-click

I am unable to move items in GUI interfaces without using the number keys. This makes it impossible to play Minecraft. To recreate: Open Minecraft and play any world, you will be unable to move items using the cursor. Below is the world I tested it in. The one I discovered it in is 26 megabytes, so I can't upload it to show you. Download it here: http://www.mediafire.com/?5gtvohzv0i8jnhn