The GUI mode does not deal nicely with 4K displays. It does not appear to inherit the preferred zoom scale for the monitor from Windows 10. The result is a TINY little window with unreadable text. Grabbing the corner of the window resizes the window, but there is no way to rescale the text. Further, the GUI doesn't remember the preferred size and position after closing and reopening.
The image viewer window is worse. It also opens a tiny window with a tiny picture. Dragging the window larger works fine, but the image doesn't rescale to fit the window if the image is small. Turn off Zoom fit and you can zoom to make it readable. Turn on Zoom fit and it goes back to a tiny image in the corner of the window.