Arviel, glad you sorted it out, you only need to play with custom coordinate in retroarch to fit overlay correctly on your screen, it’s the same aspect ratio 16:10 as my resolution 1680x1050, and yes that’s the correct coordinate for 2560x1600 resolution and save overlay per core with save core overrides
Here is example, open image or overlay in gimp and use Rectangle select tool and read position and size
Like you see for that nintendo overlay coordinate is 181 30 1318 980
My new fixed nes overlay
retroarch settings: aspect ratio index=custom, integer scale=off, custom viewport x=181, custom viewport y=30, custom viewport width=1318, custom viewport height=980
link for download https://drive.google.com/file/d/0B_4Aw-pP9z4eRm1XNjNyTjNwVnc/view?usp=sharing
My snes Donkey Kong Country 2 overlay
settings in retroarch: integer scale=off, aspect ratio=custom, custom viewport x=282, custom viewport y=108, custom viewport width=1115, custom viewport height=834.
link for download https://drive.google.com/file/d/0B_4Aw-pP9z4eckozVmlWU2RvTWc/view?usp=sharing
Super Metroid snes overlay
settings in retroarch: integer scale=off, aspect ratio=custom, custom viewport x=183, custom viewport y=43, custom viewport width=1314, custom viewport height=965.
link for download https://drive.google.com/file/d/0B_4Aw-pP9z4eb3VGNlctdkhvUUU/view?usp=sharing
super mario world custom overlay
settings in retroarch: integer scale=off, aspect ratio=custom, custom viewport x=183, custom viewport y=43, custom viewport width=1314, custom viewport height=965.
sony playstation overlay with natural background
My new updated sega genesis overlay
settings in retroarch: integer scale=off, aspect ratio=custom, custom viewport x=287, custom viewport y=128, custom viewport width=1106, custom viewport height=794.
Sega genesis sonic the hedgehog 2 custom overlay
settings in retroarch: integer scale=off, aspect ratio=custom, custom viewport x=287, custom viewport y=128, custom viewport width=1106, custom viewport height=794.
Here is my tomb raider 4 the last revelation overlay
https://drive.google.com/file/d/0B_4Aw-pP9z4eTXRpdkI4emh0b1k/view?usp=sharing hope you enjoy.
Tomb Raider 3 fixed custom overlay
Tomb Raider 2 fixed custom overlay
note: For this overlay i must decrease gameplay area to resolution 1024x768 wich it’s not good to remove weird squishing
Snes overlay based on North America console. Fixed background color.
Exodus in other thread inspired me to make samsung crt tv flat overlay for 16:10, set overlay opacity to 1.