ZDoom

Is it possible to have the option be write-in (going back to whatever the last working option was if the user types in something unparseable or unavailable)?

This is such a rare use case that you may just set the CVar directly. The menu option is not a good idea because it is very hard to determine what should be set there. My last CRT monitor even reported different capabilities for different resolutions so having everything it listed in the menu would have caused more harm than good.

Yes, I get your point, but in most cases, most programs, including GZDOOM, tend to pick what they consider to be "the best refresh rate" for you - but in most cases is not right.

In my case for example: My monitor works with 60 or 75 Hz at the native resolution, but 60 Hz is the recommended by the manual. The programs just take the highest as granted.

Problem is, there's not a lot of reason to change the refresh rate of your monitor these days versus ten years ago. Especially since most monitors today uses only one refresh rate. Then again, up to the developers of GZDoom. Just through my two cents out there.

Add option to change the Refresh Rate at Video Options - And maybe set vid_maxfps as well