Java 7 64-bit, Windows 7 Professional 64-bit
When you have the Beacon block config dialog opened and pick up a block in your inventory,
the block changes the lighting and now is fully lit from all directions.
Steps to reproduce
1. Place down a beacon block and open up it's config dialog (right click).
2. Take up and any block (not item) in the inventory as if you were to move it around.
3. See the lighting on the block changing from when it was placed in the inventory.