Hello Keith,
I looked into the issue. We're using MFC which isn't inherently DPI-aware. Microsoft has put the burden of supporting multiple DPI environments squarely on the developer. If we were using newer Microsoft frameworks, DPI-awareness is automatic. PM6 and Photo Mechanic Plus (v6) will likely be the last apps that we'll use MFC on. We're planning to switch to a cross-platform user interface framework for version 7.
It's just not feasible to add dynamic DPI changes in version 6. It would be a tremendous amount of work that we would essentially throw away when we develop version 7.
-Kirk