I am using Dymola 2021 and 2021X, the underscore doesn't show in any models. I tried to reinstall Dymola and adjust the setting option of the text editor, but the problem still exists.
My questions are:
Is this some kind of bug in the new version?
If not a bug, how to fix this issue?
You can start Dymola with a different font as follows (as described in the full manual on page 495, "Developing a model|Tools>options|General group settings|Base font size")
"C:\Program Files\Dymola 2021x\bin\Dymola.exe" –fixedfont
"Lucida Console"
or some other font than "Lucida Console" - I hope you have some that works; there's also plain -font for the non-fixed width font.
As far as I see this setting isn't stored anywhere so you will have to make a short-cut to Dymola and use that every time.
I have never seen this behavior before and it works just fine for all installations I have seen. It seems you have changed some fonts, maybe on operating system level, could you change these back? Default is sans-serif for menus (see screenshot), you use a font with serifs.
Also, a line length of 50 is very questionable, the default 80 is a reasonable MINIMUM.
Can you try and reset all Dymola settings, like this:
