Not high DPI-aware. If using on Windows 7 64-bit and having high DPI-aware issues, install 32-bit version, not 64-bit. Then right-click on the executable, Properties, Compatibility, check Disable Display Scaling on High DPI Settings.
This will remove the blurry interface and bring it in focus again. Some interface text will be smaller, although still readable (in my case at least).
Weird water-heater metaphor. No wonder this is a German piece of software. Engineers, the lot of them.