Somewhere in 4.7.x the QPixmap::Copy(x,y,w,h) has lost the ability to handle alpha channel in images.

Example, load image with transparent parts.
Do a copy using the method of a part of the image.

In 4.6.x you will get as you would expect: clipped part of the image with transparency.

In 4.7.x the transparent parts will be entirely black.