Usually you can click then move around the mouse to move around items in your inventory, In these versions I had to click and drag, after reverting to 1.4.2 it worked fine. Also I can't combine stacks meaning say I have 2 stacks of Mossy Cobblestone, One of 12 one of 15 if is was to put the stack of 15 over the 12 it would not produce the desired effect of 27 it would just do nothing.