I have a 1920x1080 pixel display. When I use gthumb on a 2480x3508 image, it displays the entire image at 17%. If I then click on the "Rotate" button, the image expands (the bottom now says it is at 18%), but it appears that only the top 2400 (of 3508) pixels are displayed. There are no scroll bars or anything, so I can't get to the bottom of the image. Expanding the window to full screen leaves the scaling of the image the same, but now gives me about the top 2700 pixels in the working window, again with no scroll bars or anything. So if there is an edge on the bottom of the image that should be horizontal, and I want to align that, using the rotate operation, it's impossible. (well, not impossible, I first invert the image, to put the edge to the top, then rotate the image (since the alignment line is now at the top), then invert it to get the correct image back.)