If you mean the pet bar, that's Masque_PixelSkin. It looks like it's pixel perfect with crisp borders but it's not. I always have to try different decimal values to get the best result. That takes most of my time creating UI, playing with numbers. For example, that pet bar is 0.685 in scale, -329 in X and 265.65 in Y and it still isn't perfect because one of them is always slightly blurred or the gap between two of them isn't there as it should be and I can't have 0.80, 0.90, 1 etc. in scale because it's too big.
I think that background (kgPanels) behind them kinda hides these irritating details.
Here's a macro for pixel perfect UI scale for specific resolution btw, if you didn't do it already. It didn't seem to do much for me, but maybe it can help a little.
http://www.wowinterface.com/forums/s...ad.php?t=31813