yep. you have to change output as well

I tried opengl, ddraw and direct3d and seemed the same. Been by default just using direct3d.

fullresolution=0x0
output=opengl

should be different from direct3d, as that is not a valid option.
But maybe take a screenshot, I might be misinterpreting what is missing.
of course if you are playing a non-16:9 on a 16:9 monitor then surely some parts are going to be black.

Oooo will try that. Will report back in a few minutes.
I am using 4k 16:9

OK tried it... same with image going beyond screen borders but lost that crisp image.
Isn't res set to 0x0 same as desktop?

Well hells bells... I found the culprit! It was Windows scaling! Because my resolution is 4K, Windows defaulted me to 150% to help with text being to small.
I changed it to 100% to try and bingo! Fullscreen without the image going past the edge!!

Thank you for sitting with me and helping me through my questions!

Excellent, but this shouldn't happen with 0.74-3 I think. (the windows scaling causing a too large size to be picked, but maybe I made mistake in that code)
Are you using the latest version ?

I think one of the SVNs from 6 months ago!

I can try to revert it to try.

actually this maybe be harder for me to do. All my DOS games are using an SVN version but the windows (3.x/95) games are pre-made on REMOVED
I can only asume he used the 0.74

I will download the latest release and work it into my DOS games folder. Let you know it just a few.

Ok updated to 74-3
And opengl 0x0 worked perfectly with my scaling sitting at the default 150%
I will just have to figure out how to apply this version into these older build for premade win games that is using an older DOSBox.

Again Thanks a million!!!