I think I mentioned it before, but since I cannot remember your reaction, here's a suggestion for improvement:
The Image Viewer node is very helpful but in some way also very inconvenient, when jumping from row to row and from column to column. Think of a visual inspection of the result of multiple thresholds applied to multiple images. So, can you please implement the use of the arrow keys as an alternative to the four buttons at the bottom of the screen? I would realy appreciate this.