Okay, this is a weird one. Observe: That's right, if you happen to drag and drop an item into the space next to the right-most inventory slot in the 5th row of your backpack, the item is placed in an invisible 9th slot in that row. Any standard item can be placed there and the game treats this spot exactly like a standard inventory space, as near as I can tell. An item in the this "non-slot" will even persist through a save-and-reload. It only happens with the 5th row (and only on the right-hand side) and none of the other rows; that's the first thing I tried after seeing this. Edit: Apparently this "non-slot" is simply some sort of graphical glitch, because now I have an empty space in my backpack, but have an item in the "non-slot", and... YOUR INVENTORY IS FULL!
Very old bug; it doesn't only happen on the fifth row but it counts as the first slot on the next row (which is why you could only put it there). It's still on the todo list somewhere.
Huh, funny that I never ran across it before. In any case, since it's purely cosmetic and doesn't give you extra inventory, it's pretty much a "who cares" bug. All those screenshots for nothing! *cry*
