Preview image aligns to subpixels on non-Retina displays

[75th]

ImageAlpha 1.5.1 MacOS 10.13.3

I think the title is an accurate description of the problem. When dragging an image's preview around at 1x zoom, it changes the antialiasing of the image, rather than always showing true 1:1 pixels. (The image does not snap back to pixel-perfect when you stop dragging.)