1:    when you pick up an item (in creative) in your inventory then hold the "Pick Block" key bind, if the key bind is set to a button on the mouse it creates stacks of items over empty slots, how ever if the button is set to something not on a mouse, the feature stops working.

2:    If the key binds for [Attack/Destroy] and [Use Item/Place Block] are switched to something other than [Left Button] and [Right Button] respectively, they do not switch while inside the inventory and remain as [Left Button] and [Right Button] respectively.