When I zoom into an image and pan with the mouse, there is distortion in the movement of the image. It sort of jumps per 'zoomed' pixel rather than real pixels, but also seems to base one side or the other as an origin while stretching the pixels on the way to the other side to get the full 'zoomed' pixel step. (The scaling method selected doesn't seem to affect the behavior.)
See attached video comparing XnView on the left with DOpus Image Viewer on the right.
Edit: I forgot to enable display of the cursor in the recording, but it should be pretty obvious what's happeneing.
Looks like there is still an issue with 13.24.2 regarding image distortion.
The panning seems good (fast fix, thanks!) but there is still distortion when resizing the window. It's forcing a certain number of 'zoomed' pixels to fit within the Viewer dimensions, and squashing them to keep the same number without any partial ones until the threshold is reached to increase/decrease the count.
Only happens with Accelerated rendering enabled. I also noticed that when enabled, the image adjusts/pans by full 'zoomed' pixel steps, while when disabled it adjusts by real pixels instead. I don't know if there is an explicit intent for this behavior difference though.
While testing this, I also saw a glitch with some scrollbar elements not being re-drawn properly while resizing the Viewer window:
