When the main display is high DPI and Windows is scaling the non-aware apps down, EmEditor looks like this:

..the font is too small, when you drag EmEditor onto a low DPI screen, the system scales it down 2x and the text becomes unreadable:

When the main display is low DPI and Windows is scaling the non-aware apps up, EmEditor looks like this:

..this is how most non-aware apps appear when scaled up, ideally EmEditor would register itself as per-monitor aware and render fonts crisply on both screens.