Hi there,
I'd like to suggest a preference option for the (standard by now) automatic resizing of the filter previews - something like:
[ ] always resize
[v] only resize previews too big to fit on screen
(and eventually [ ] never resize, although this option might not be too useful, since you can't access some controls / the OK button anymore when dealing with high-res video on small screens)
(Background: I'm working with almost only SD resolution files on a 24" screen with 1920x1200 resolution; in ~90% of all cases, I untick the resizing option (every time..) because I find it far more convenient to work at 1:1 scale and reasonably sized windows)
+1 for never upscaling, ideally the canvas should be resizable by the window. On the todo list.