You know what, I realize that her boob window is very controversial, but my reasons for being against it are deeper than most people's. My main argument is why does she even have this? I know this is a way for her to embrace her femininity, but let's do some simple sexual math here. If you're a female superhero, chances are not only are you really busty anyway but you wear spandex. The whole point of the latter is that it's supposed to be skin tight to leave nothing to the imagination. So that boob window is the equivalent of making a flesh-eating zombie wear a necklace of shrunken heads. It's redundant.
Unfortunately, this does seem to be what most people know, so even if Power Girl didn't like this design, she has to stick with it to stay popular.