The new popup choice dialog is great, but it would be really nice if it could also (optionally) filter the image like the main window does. Since the image will typically be scaled down a lot to fit the popup, it tends to suffer even more from aliasing artifacts.
It might be worth only using the fastest filter for this, as the popup is supposed to be fairly low-overhead, but even that might not matter if you display the unfiltered version first and then draw the filtered version over it afterwards (just like the main window).
Speaking of which, do you calculate the filtered version of the image in another thread? I haven't actually noticed a pause, but maybe it's just quick enough to not be noticable.