Command Block Gui Is openable when above 255

What I expected to happen was...:
for the command block not to open when it was at 255 and right clicked on the top face of it.

What actually happened was...:
It opened, which doesn't happen for blocks like furnaces and crafting tables

Steps to Reproduce:
1. First put a command at Y=255
2. Next go above Y=255 and right click the top of the command block(make sure you click the top face)
3. After that place a furnace at Y=255
4. Then go above Y=255 and right click the top of the furnace (make sure you click the top face)
5.Notice the command block will open and the furnace won't
5. Compare results from