If using PlayOnLinux, which uses Wine in the background:
The following worked perfectly for my program (LTSpice).
Open PlayOnLinux --> click "Configure" button --> Wine tab --> Configure Wine --> (this opens up the "Wine configuration" window for this specific app in PlayOnLinux, which is the same kind of window you see when you run winecfg
from the terminal) --> Graphics tab --> Drag the Screen Resolution slider up from 96 dpi to perhaps 120 dpi.
Fixed!
Examples
Before (96 dpi):
Wine configuration window where I set this:
Running LTSpice in PlayOnLinux (which uses Wine)--showing the Control Panel in LTSpice (notice the small font in the center window, and the small File, Edit, Hierarchy, etc. dropdown names at the top, as compared to the 144 dpi version farther below):
After (144 dpi, for example):
Wine configuration window where I set this:
Running LTSpice in PlayOnLinux (which uses Wine)--showing the Control Panel in LTSpice. Notice how much bigger the center window and File, Edit, Hierarchy, etc. dropdown names at the top are here as compared to the previous screenshot in the 96 dpi example above):