I
think (and I emphasize think here) that the internal DDS display function expects images to be square (height=width.) I noticed that when I open it for my target window mod (non-square DDS) it stretches the DDS to display as if the height were the same as the width (it isn't. Not by a long shot.) Haven't done too much testing with this since I tend to just grab the corner coords in photoshop and type 'em in by hand, but I figured y'all might like to know.
