Since one of those "big update" for Windows 10, that occurred months ago, I started having a peculiar problem with Mugen 1.0/1.1 running 4:3 resolutions (eg.: 640x480). From that update onward, any screenpack with the cited resolution would result in a "zoomed in" screen - cropping the top and button of the game outside the visible monitor area - when entering fullscreen mode.
Changing the properties of the mugen.exe, such as compatibility mode, force 640x480 resolution, etc, wouldn't change a thing.
I suspect that this issue has something about my monitor native resolution of 2560x1080 (21:9) + the Win10 update, because I haven't seen anyone else talking about this issue.
Ok, fast forward to the present, I have found a solution to my problem and I want to share it, mainly because, aside from fixing the resolution problem, I believe this might help to improve Mugen stability in general, but of course, much more testing is required before taking it as granted, so please leave feedback in case u try it.
The solution is called DXGL, an open source dll wrapper that aims to replace the Windows old ddraw.dll library.
I will quote from the official site:
Spoiler, click to toggle visibilty
So, let's get started:
First, BACKUP your stuff!!! Better safe than sorry
Second, go to your mugen/data folder, open mugen.cfg and set the RenderMode to OpenGLScreen (if mugen 1.0) or to OpenGL (if 1.1; although OpenGLScreen also works with mugen 1.1, I believe it's better to use OpenGL)
Third, go to the official DXGL site and download and install the latest version:
Now, run the "Configure DXGL" executable and then:
1 - Click on "Add" and add your mugen.exe
2 - Choose "Aspect Corrected Strech" from the Video Mode drop down menu
Hit "Apply" and u can already check, a "ddraw.dll" should appear alongside your mugen.exe and the resolution should already be working!
But now, there's still one more thing to do!
By default, all your options should be saved within the Windows registry, but you'll probably want to save your configuration locally, so it become portable and sharable.
So, click on the Advanced tab:
And click "Write ini file..." (use the default options)
Now, a "dxgl.ini" should be created in your mugen folder, alongside the mugen.exe and the ddraw.dll
And that's it! Currently I don't have much time to test it, but I was able to run Mugen 1.1 in Windows 10 w/o experience any crashes or anything else, but please leave feedback regarding this, in case u also test it
It's also worth mentioning, that the latest version of ReShade should work just fine if u use the DXGL dll, just make sure to choose OpenGL when installing ReShade.