Hello. I think the fullscreen/windowed stretch mode in 86Box could be improved (ideally).
Currently, in windowed mode, the emulator displays something like this by default:

Obviously the aspect ratio is completely wrong because on a real hardware the image would be stretched to a 4:3 aspect ratio.
It is possible to select the Force 4:3 display ratio option, but this is not a solution that will always work because, as I will point out later, there are some DOS resolutions that should not be stretched to 4:3.

There are more options in full screen but I'm still a bit confused here too...

• The Full screen stretch option is useless in my opinion. Who want to ruin the aspect ratio by stretching the image horizontally and/or vertically? I can't find any use cases for this option, maybe someone can list some.
• The 4:3 option has the same problem described above in windowed mode: all resolutions will be stretched to 4:3, even those that shouldn't. For example, the DOS game Jazz Jackrabbit uses a resolution of 320x199 at 60 Hz, which shouldn't be stretched.
• The Square pixels (Keep ratio) option can be useful in some Amiga ports for DOS that are incorrectly stretched vertically even on real hardware.
• The Integer scale and 4:3 Integer scale options have the same problems as (respectively) Square pixels (Keep ratio) and 4:3, but with integer scaling (which on 1080p always results in black bars also above and below the image so I always avoid it).

In my opinion, in windowed mode, the Force 4:3 display ratio option should be replaced with something like Fix aspect ratio which would only stretch non-square pixel resolutions like 320x200, 640x400, etc. The same should be applied in fullscreen mode to the 4:3 and 4:3 Integer scale options.