Well, I can fullscreen with it once the visual settings are updated with gens_netplaysave. If I just use gens_netplaysave.exe config file the emulator crashes every time when I switch to fullscreen.
Anyway, I attached gens_netplaysave with the updated cfg file from gens11b with 2on2 rom, classic 94 rom and the classic playoff rom. Also attached the config file for people who have everything setup and just want to drop that file in there so they can play fullscreen.
Gens.cfg gens_fullscreen_netplay.zip