When using the 'Pick Block' control on a monster spawner doesn't select the item in the inventory, and in creative, doesn't get a monster spawner.Pick block works for other non-survival-obtainable items such as command blocks, even when in survival (obtained using cheats). Tested in 1.9, 1.9.1, 1.9.2, 1.9.4, 1.10, 1.10.1, 1.10.2, 16w39a, 16w39b and 16w39c but the bug tracker won't let me add all of these versions.