thanks for posting this.
i've used it to successfully open and edit the standard retina display sms bubbles to my own colour.
i've noticed, however, when sending text messages, the bubbles jitter and 'skip frames' when sending and i can only assume that it is because the .png files aren't encoded properly for fast rendering.
apple has encoded the .png bubbles for fast rendering.
the iphonefixpng program alters the files to be viewable and editable .. i then changed the colour of the bubbles through photoshop.
how do i 'un-alter' what iphonefixpng does to revert the files back to the way that apple has encoded for fast rendering?