Middle-click + ctrl command does some useful things like picking up chests with items stored inside or getting a sign with text stored in your inventory, however, this command does not work with some blocks you would expect it to work with.

1) Beehive / Bee Nest

Breaking a beehive normally in creative drops the beehive with honey level stored, doing the same thing with middle-click + ctrl gives you completely different beehive or bee nest without any honey inside

2) Cauldron

Does not keep water level, gives you normal cauldron instead

3) Composter 

Does not keep soil level, gives you normal composter

4) Jukebox

Does not keep the music disk inside (gives you normal jukebox with some NBT tag nonetheless) 

5) Lectern 

Does not keep the written book (gives you normal lectern with some NBT tag nonetheless) 

List of things that work as intended:

Any chest-like container

All furnaces

Beacon

Campfire