Apologies, I didn't see this thread here until today. However, I did answer your email to me with the reason why you're seeing the white shadows. For posterity, here's my email reply:
Some background on how Frameless works might be in order here. For all supported image formats except for GIF files, Frameless uses the standard Win32 picture control. That said, the control DOES support GIFs but not animated GIFs. So, for GIFs, I use a third-party control that supports animated GIFs. However, based on your sample, that third-party control doesn't appear to support the type of transparency in your file. Unfortunately, there isn't much I can do about it; I'm somewhat at the mercy of the control.