GQview is such a great program, I use it as my primary image viewer. Mostly I watch photos or other medium to high resolution content. Here good antialiasing is really great. From time to time, though, I have to look at some icon or other tiny image. Having a 16x16 pixel icon displayed in an 1000x1000px pane with smoothing doesn't make a lot of sense; in this scenario I'd prefer to see single pixels. Going through the preferences is too much bother, however, so mostly I don't.
A simple keyboard shortcut to change this setting, i.e. enable or disable aliasing, would be great. Probably the UI in the prefs would need to be changed too, as the selection of the aliasing mode should be visible even while aliasing has been disabled. So a checkbox instead of the "nearest" entry in the dropdown list would seem right.