Kega Fusion (v.3.64) Windows 10 Alternate Fullscreen Fix
After trying every solution on the web, including this:
https://youtu.be/cmpKrxBvR4c
I screwed around a bit with other settings, and this worked for me along with a few people I know having the same issue, to which the solution above did not work.
Not sure if this is important, but using a GeForce 1060 trying to output to 1080p on this particular setup.
Written steps:
1) Right click Fusion application, and select "Properties"
2) Go to "Compatibility Tab" then go to "Change High DPI Settings"
3) Check the box at the bottom marked "Override high DPI scaling behavior" while leaving the drop-down set to "Application"
4) Click OK to exit this screen, then click APPLY to exit the "Properties" menu
5) Reload Fusion
Afterwards, all should be well, with the output properly centered.