Mob Spawner Inventory bugs

Hi

To reproduce:

1) In creative mode, /give (yourself) mob_spawner

2) Do anything with the spawner in your inventory, ie. move it around. Now it's corrupt, so move it back to your hotbar and try to place the spawner, and it will disappear (bug 1)

3) Shift-click the X, and it won't be deleted (bug 2)