"Inspection window" in lightable
Currently, if we want to assess the focus of an area ourself (Ctrl-z is not always reliable, even when it works) before rating a picture, we have to open it in darkroom to be able to scale it to 1:1, then go back to lightable. It's OK for a few pictures, but when you are rating a few hundred pictures, it becomes tedious.
I suggest implementing an "Inspection window" where the thumbnail is in darkroom (to keep a coherence between both UI). But, contrary to darkroom, the zoom would be applied on the thumbnail (so we don't have to change the layout of the lightable each time) and show the area of the picture under the mouse pointer. This would allow to assess quickly the eye of a portrait or the center of a flower without disrupting in the rating process (i.e. no switching to darkroom, no changing the layout of the lightable, etc.).
Also, if you develop this zoomable window, it would be practical to have it in darkroom too, instead of the fixed thumbnail. While not as critical, there are several modules where we want to assess the impact both on the entire image and at 1:1 (denoise, sharpen, etc.). Having the same zoomable window where the fixed thumbail is would allow to assess both without zooming in, zooming out all the time.