See 1st pic room 15903, lower right corner.  Jack is in the wall, just above the number 7 in the pic.  You can't see him but he is there.  The blocks are transparent, so Jack has nothing to jump onto.  He was up above and fell, then ended up in this spot.  He can jump to the right and end up in room 15904, but as you can see by the pic, the blocks now keep him from moving to the left, which is pointless really, bcos there are no blocks for him to jump onto in room 15903.

I am operating a Mac OSX 10.8.  I believe that this is the High Definition game.

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