This is a well-known issue on Windows 10 with some high dpi touch screens, especially on laptops. Do the following to fix this problem:
- From the main menu, select EDIT > Global Preferences.
- On the Preferences window, select the Core UI Resources section.
- Disable (uncheck) the Automatic UI scaling option.
- Set UI scaling factor to 1.5 if you are working with a 4K monitor. For a 5K screen, the correct factor is 2.0.
- Press F6 or click the circular icon to execute globally.
- Exit PixInsight.
- Wait a few seconds, then run PixInsight again.
This has fixed all of these issues consistently in almost all reported cases. Sorry for the inconvenience. Of course, the next version 1.8.5 of PixInsight does not have this problem.