You can't middle click to get a block with a sword

You can't middle click to get a block with a sword with a full hotbar and a command block in the inventory

I expected to get a block

Nothing...

1)Fill hotbar with different items and one is diamond sword
2)Make sure the one next to the sword is a command block
3)With Diamond Sword middle mouse button click on another block
4)Nothing happens

ScreenShot: http://prntscr.com/4k9m33