[Bug 42740] Icons with transparency no longer rendering correctly

https://bugs.winehq.org/show_bug.cgi?id=42740

--- Comment #6 from Johannes  ---
My apologies, there is indeed a white background on regular Windows as well.
I'm not sure what I did different the last time I tested it.

However, there is still a difference (see attached screenshot) that might be
somewhat relevant. The upper part of the screenshot is Wine 2.4, the lower part
Windows 7. I think Wine applies transparency to a few pixels there (see the
last two icons), while Windows doesn't.