I bought a new Windows PC. Since then, the Pkhex is blurry. When I optimize the DPI settings, that's better but the box editor is tiny.
Now I found the solution. it's very simple: Use the same "Screen resolution" as in my old laptop: 1366x768
Right-click on an empty area of the desktop, then click on Display settings....
Now the Pkhex runs as usual. No blurry, no tiny.