IMHO there is a need for improvements in the gray marker's refining workflow
I hate that they move when I just wanted to validate their current position.
In my opinion, when you click on the marker, you could open a magnifier window with accept and skip icons where the user could reposition the marker by dragging, validate the gray position as is calculated and turn it blue, or skip to close the magnifier letting marker remain in gray status. (Options for magnifier might be: magnification factor, show upsampled and border/contrast enhanced crop, crosshair cursor on button down, automatic target detection by key press... )
Thanks
JMR (was LFA)