Version: 4.0.3
OS: Windows 8
When I load a picture, and go to image resize or image canvas size option in the image menu, Paint.net now shows the picture as being 68.3MB large, when in reality it's only 5 or 6 (as shown by Windows Explorer). However, when you go through the motions of saving the image and the preview box appears, the file size is correct.
I can provide more information should it be needed