Inventory icons not aligned properly?

[intermediateuser]

So I have a GUI populated with a player's inventory.  In default Minecraft resolution, the inventory icons line up properly.  But when I maximize, the items are a bit to the left and too high up on the screen.  Any idea why this might be?

 

Also, I can't seem to pick up any of the items... clicking the items seems to drop them on the ground.

 

Relevant code:

for (int row = 0; row < 3; row++)
        {
                for (int slot = 0; slot < 9; slot++)
                {
                        addSlotToContainer(new Slot(playerInv, slot + row * 9+9, 133 + slot * 18, 141 + row * 18));
                }
        }

        for (int slot = 0; slot < 9; slot++)
        {
                addSlotToContainer(new Slot(playerInv, slot, 133 + slot * 18, 199));
        }

[ObsequiousNewt]

The entire Container code would help. GUI code might be telling as well. As it is, I can't see anything wrong.